###### A message for this time of year

###### It happens every year, and especially right now. When a storm threatens, we consider our options in a power outage. Will we be lucky again? Or unlucky again? Truth is, it’s better to be safe than sorry. A portable generator is a good investment even when the weather is nice. If you’re visiting this site for a possible emergency, or if you already own a portable generator, just remember, “Always be safe!”

###### To save you some time, many new generator purchasers are only interested in one that can handle their refrigerator/freezer in a power outage. If that is you, look at one that provides at least 2000 surge watts. Although most refrigerators require less than 1000 watts to run, when the compressor cycles on, they need the additional watts.

## What size?

You’ve made a decision to get a portable generator. Great! A common question that I get from shoppers looking for a portable generator is, “What size portable generator do I need for home use?” The best answer to this question is not very popular. The answer is, **“It depends”**.

Many people go make their portable generator purchase and wish that they had considered all the factors first. Let’s face it, generators are expensive and you don’t want to waste one while you purchase the one you should have bought in the first place.

Take for example two best selling generators. The Earthquake ig800w is an 800 watt inverter generator that can only power one or two items at a time. The equally popular Generac xg8000e is an 8000 watt generator that has enough power to hook up to your home’s power panel to supply most of your needs in a power outage.

Why one group of people think that one size is what they need and another group of people think a completely different size is what they need is why “it depends”.

For a better explanation of “it depends”, read below and take a look at the handy table which provides the estimated wattage requirements of some standard household devices and appliances.

## Running Watts vs. Surge Watts – What’s the Difference?

The two columns on the table that you need to understand are the “running” watts and “starting” or “surge” watts. The difference is that all devices require a certain number of watts to run continuously AND some require an additional number of watts to start or to cycle on. This is why portable generators are rated for their running watts and their surge watts. Running watts are generally 90% of surge watts on most portable generators. A generator should not be expected to run continuously above their rated running watts.

device | running watts | starting (surge) watts |
---|---|---|

Electrical Water Heater (40 gal.) | 4000 | 0 |

Hot Plate | 2500 | 0 |

Electric Stove - each element | 1500-2500 | 0 |

Window Air Conditioner - 12000 BTU | 1200 | 1800 |

Microwave - varies | 625 | 800 |

Well Water Pump | 1000 | 1000 |

Sump Pump | 800 | 1200 |

Refrigerator Freezer | 800 | 1200 |

Deep Freezer | 500 | 500 |

Furnace Blower | 800 | 1300 |

Computer | 800 | 0 |

Television | 500 | 0 |

Stereo | 400 | 0 |

DVD Player | 100 | 0 |

Box Fan | 300 | 600 |

Clock Radio | 300 | 0 |

Light Bulb | 75 | 0 |

Radial Arm Saw | 2000 | 2000 |

Circular Saw | 1500 | 1500 |

Miter Saw | 1200 | 1200 |

Reciprocating Saw | 960 | 1040 |

Electric Drill | 600 | 900 |

Air Compressor (1 HP) | 1500 | 3000 |

Garage Door Opener | 480 | 600 |

Security System | 180 | 0 |

Resistive type devices do not require surge watts. These are generally heat producing devices such as light bulbs, toasters and coffee makers. Devices and appliances with an electric motor in them require an additional requirement of watts to “start” them. Starting can be as simple as flipping a switch as in a hair dryer or power drill. “Starting” in a refrigerator is quite different and will start and stop repeatedly. Listen closely to your refrigerator and you will hear it cycle on periodically as its fan, compressor or defrost cycle starts. These “surge” watts can be sometimes be two or three time the watts necessary to simply run the device.

## What Size Portable Generator Do I Need?

When calculating the watts that you’ll need, you must consider this extra watt requirement. In reading this table, take a standard refrigerator/freezer for example. To continuously run the unit, you need approximately 800 watts. However when the compressor kicks in, it requires a the additional 1200 surge watts. So it takes 2000 watts to supply ongoing power to your refrigerator/freezer.

As it settles into its running watt requirement of 800, the difference of 1200 watts can then be used to power something else. If you have a low to mid watt generator (up to 3500 running watts) you may opt to run your refrigerator most of the time and and rely on it keeping itself cold with the doors closed, then unplug and switch the power to other needs.

Be aware when looking at other tables on other sites which explain estimated wattage requirements. Some include the running watts already added in the surge watt column.

So to give a better answer than, “It depends”, you need to ask yourself, “What do I need the portable generator for?”

- emergency use in power outage situations
- to hook into your home’s power as a standby
- for now and then use around the house
- for use on the job in remote locations away from electrical outlets
- for camping, tailgating, RV use
- all of the above?

Now ask yourself, “When using the portable generator for my purpose, what will I want to supply power to, and how many at the same time?”

Here’s a good rule of thumb, add up the running watts for the MOST devices that you’ll need at any given time. Then add in the highest surge watt requirement for any of those devices.

You then have the minimum watt requirement for the generator you’ll need. With well timed use of devices that don’t need to be used constantly, this should be enough power for you. If not, remember that you will have to unplug one or another to have enough wattage available. But here’s some wise words, no one ever said, “I wish I had LESS power.”

Let’s say for example that you have a power outage and you want to keep your refrigerator/freezer running continuously. According the the estimated watts on the table, you need 800 watts to power it, but will need periodic “surge” watts of 1200. Now if you’re running other devices off of the generator at the same time, for example a TV, stereo, and several lights, for an approximate total of 2000 running watts, and you are drawing at, or near the peak rated watts of your generator, when your refrigerator “surges” and you exceed the rated watts of your generator, you can trip the breaker and you’ll lose power output.

## What Do I Need to Know about Watts and Amps?

Remember, this table is for convenience only and the figures are only estimates. Most appliances have their watt requirement (or Amps) usually printed somewhere on your device. The watts that you read on your device are not always the wattage that it will require. For example an 1100 watt hair dryer will produce 1100 watts of heat, but require more watts than that to power it. More accurately, if you know the Amp draw of your device, there is a handy formula that will let you calculate your watts:

**Amps x Volts = Watts**

Volts is nearly always 120 in the US. If you know that your device requires 10 amps, then 10 amps x 120 volts = 1200 watts. Similarly you can calculate your Amps with the formula:

Amps = Watts/Volts

So you know your appliance is 1200 watts. Divide that by 120 (Volts) and that gives your your Amps equal to 10.

Sorry for the math lesson, but here at the *GeneratorGrader* we want to make sure that what you should know is available to you. See the article titled How a Portable Generator Works for a more detailed explanation of volts, watts and amps.

After you determine the size that will make you happy, you might want to consider other factors in determining the right portable generator for you. There are noise considerations. Whether you want to fuel with gas, propane, or diesel, or a combination of two or more fuels. Whether you require pure electrical energy for sensitive electronics. As you can see, when asking yourself, “What size portable generator do I need?”, you might want to arm yourself with more knowledge available in the other articles on this site.

In summary, ask yourself these pertinent questions before you decide on power alone. There is quite a difference between a 2000 watt All Power and a 2000 watt Yamaha inverter. More than just the $800 price difference! Once you know what size you want, know the advantages of an inverter type vs. a standard generator.

**Filed under: **What Size I Need

Hello:

I came upon your article in my search for the proper size generator for my sump pump. Unfortunately the manufacture of the pump I bought [ Murray ] only will give me a guess as to the staring amp’s [ 2x to 3x ] the full load of 6 amp’s . I was going to buy a low price Champion 1500 watt generator, because of the light weight & seldom loss of power in our area. Your formula for a sump pump show’s a 1.5x surge.

120x6x2=1400 watt’s

120x6x3=2160 watt’s

120x6x1.5=1080 watt’s

The price difference between the Champion & a light weight Yamaha 2000 watt is $800.00. Given my choice what would you

do ?

Thank you

Hi Bob,

The estimated surge (starting) watts on the table above is for estimation only and is on the low end. Does your sump pump have a faceplate that states the running watts?

Unfortunately, one of the main complaints by users of portable generators is that they don’t run at their maximum rating very well. Let’s say your sump pump is rated at 800 watts. If, as Murray suggests, you will need up to a 2400 watt surge rating. To purchase a unit near this maximum is a gamble. You’d hate to spend all that money on something that in the end bogs down on you.

If your power goes out infrequently as you say, you may not need the lightweight or quiet of an inverter like the Yamaha (unless you plan to use it for other things which makes it a good choice).

I can’t spend your money for you, but I recommend buying as much wattage as your budget will allow. If you were considering the $900 2000watt Yamaha, you could buy a sweet non-inverter for less than $500. You could get 5000 watts and 120/240 volt capability. You’d have no trouble with the sump pump and have the extra power to take care of other creature comforts during those outages. It’s not the most efficient use of fuel to power, but it’s an emergency.

No one ever said, “I wish I bought less power.” Let me know how it turns out.

Good luck,

Ray

Hi Peter. You can look at the information on the plate on the back of the unit. Look for Amps or BTU’s. British Thermal Units (BTU) will tell you the cooling capacity of your AC. More importantly, you can estimate that 10,000 will need almost 10 Amps. Or Amps will be listed directly.

Your AC unit may be larger or smaller than that. If you are powering your AC with 120 volts from a portable generator, use the formula Watts = Volts x Amps. If you need 10 Amps, then times 120 Volts equals 1200 watts.

This will “run” the AC. Be advised though that when the compressor “kicks in” it will require more power. This additional surge requirement could mean you need another 1000 watts available to keep it running.

Now you’ll need 2200 watts of power to run your AC. You can do the calculations based on your specific AC.

Recommendation, don’t expect a generator at the maximum rated power to meet your needs. Often, portable generators struggle at their rated power. Get as much power as you can afford so that you can run other devices at the same time.

Hope this helps.

Ray

Hi!

I want advice as to what capacity of generator i will need to buy to supply a home of 6 bedrooms, 2 deep freezers, entertainment system, 3 mid-size air conditioners,deep well water pump, and water heater in 2 bathrooms?

In contrast, what capacity is enough to handle a town home? Thanks in advance.

Hi Theo,

Thanks for the question, however it is not an easy one to answer. You must first find out the power requirements of all of the things that may be running at the same time. For example you may have 6 bedrooms, but not all used at the same time. The freezers will always be running. You can purchase a portable generator at 10kW to 15kW, but you’ll probably want to hook it up to your home’s power panel via transfer switch, especially since you want power access to so many areas (can’t run cords). That way, you can switch power around to where you need it at the time.

If you want to have a set and forget type of system, you might consider a standby generator at 20kW. It’s built in and automatically powers your home when power is lost. It is a bit more pricey and not portable, for the peace of mind and convenience. If you outages are not frequent, and cost is a factor, go large portable.

For your town home, depending on the layout with your neighbors, the placement of your unit will be a factor, however, you might be able to get by with a 7.5kW portable in most cases.

Hope this helps. Let me know if you have any more questions.

Ray

We have bought a 800 watt generator and would like to know if it will power a 5000 BTU A/C unit and a light? Please respond and let me know. Thanks so much.

Beverly

This assumes that you do not have access to the plate on your A/C detailing the Amps. If you do, use those figures or contact the maker.

The relationship between BTU and watts is somewhere between 9 and 12 BTU’s/watt. This means somewhere between 400watts and 550 watts for your 5000BTU A/C.

If it is an 800 watt generator, it is only providing 120volts. At 120volts, your amps would be between 3.5 and 4.6 depending on your A/C’s BTU/watt ratio.

Short answer is that there are enough watts in you generator to run it, but possibly not enough to start it as it needs often many times the running watts when the unit turns on.

Please check with your manufacturer or certified electrician, which I am not. Good luck.

Ray

I need to power to televisions and a speaker what size generator would I need. Or what factors do I have to consider? So lost…

Hi Amanda,

Yes it can be confusing.

The first thing to do is take the watts required to run each of the items you want to power. If you expect to run each of these at the SAME time, you must add up the wattage requirements. You’ll find the wattage requirements printed on the item usually on the back where the plugs go in. For example, two TV’s at 500 watts each and a stereo amplifier at 400 watts is a total of 1400 watts. You’ll need a generator that is rated for at least that amount as it’s rated or running watts. You can forget “surge” wattage that you’ve heard about because TV’s and speaker amplifiers should not have that. Usually only appliances with electric motors have a surge requirement.

If you get a “2000 watt” generator (as they call themselves) they are actually around 1600 running watts. This should be enough to run the items you mentioned as well as be useful at other times as well.

I’m assuming that you want to power these items aside from a home power outage. If you wanted to replace power in your home, you will probably want at least 3000 watts to 5000 watts or more for general usefulness to power more items at the same time.

Good luck,

Ray

I am looking at purchasing a 8000 watt generator for my home. I would need it to power the heat pump and refrigerator and aome lights. Will this be big enough?

Thanks

Hi Steve,

Here is my best answer. First, is the 8000 watts the running watts or the surge watts? You will want to make any determinations based on your running watts.

A refrigerator will typically need 2000 watts supplied by the generator including the surge watt requirements. Lights will take very little, depending on their wattage and how many you plan to power. The question is in the capacity of your heat pump. You’ll need to find that out. I know very little about heat pump requirements other than that they can be as large as 10,000 watts. You will be able to find out if you can check the plate near the serial number. Otherwise contact the manufacturer with your model number.

Add up all the watts of anything that you want the generator to power. Keep in mind that you can alternate the things you turn on to keep the total below the running capacity of your generator. Hope this helps.

Ray

i would like to buy a generator to run our camping fridge, how many watts would i need.. perhaps also to run lights, maybe kettle occasionally or fry pan

Hi Paula,

There are a few factors to consider. After reading this article, you know that you need to determine how many amps each of your devices require. Lights take very little. Is your refrigerator in a motor home? A camper? If it requires 5-6 amps, then you’ll need a generator that can supply 1000 watts or so. Remember, refrigerators require surge watts as they cycle. You can disconnect your fridge while you run other cooking appliances (for a short time and keeping the door closed), which might take that many watts as well. If you don’t want the hassle, get yourself 3000 watts if your budget will allow, or a 2000 watt inverter if noise is a factor.

Ray.

Hello Elmo,

More important than the cost of the generator is the capability of the generator in Volts and Watts.

There are some things that you need to know about your chop saw. How many “amps” does it require?

I’m going to guess that it is 15Amps at 120 volts. If so, then it won’t need the extra 240 Volt capability of more expensive model generators.

You can get a generator with 3500 surge watts and you should be just fine. You’ll probably spend less than $500 for that.

If your requirements are more power, then remember the formula:

Watts = Volts x Amps

That is, it your tool is 15 amps and your generator provides 120 volts, then 15 x 120 = 1800 watts. You need to buy a generator that provides that many watts. But add more watts up to 3000 to cover the surge requirements of your saw. Good luck.

Ray

Hi, above you say:

“So you know your appliance is 1600 watts. Divide that by 120 (Volts) and that gives your your Amps equal to 10. Sorry for the math lesson, but here at the GeneratorGrader we want to make sure that what you should know is available to you.”

Actually, 1600/120 = 13.33. Sorry to give YOU the math lesson. 😉 I know, I know, you had talked about 1200 watts just above that and I’m sure that’s what you meant to say. Seriously, thanks for the good info!

thanks john.

I need to run a fridge, tv , 10 lights and an electric heater. What size 3500 or 5500 watts?

Hi Russell,

The answer will depend on a few things. First the requirements of the appliances that you plan to power. For example, Your lights are determined by what wattage they are. Are they all 60 watt? 100 watt? Then your requirements for just the lights (assuming that they are all on at the same time) is between 600 and 1000 watts. Your TV probably needs around 500 watts. The heater will have a wattage requirement. Find that out and add that. If it has a fan, it may require more as would any appliance that has a starting motor in it. So your fridge definitely has a cycling compressor in it. Guess 1500-1800 watts if you plan to keep it running continuously.

So if you run everything at the SAME time, 3500 watts from your generator won’t be enough. If you schedule what is running at the same time you may be able to. Be safe, get the 5500. They are a bit louder, but not that much more expensive. Hope that helps.

Ray

Hello, I have a small concession business that I am trying to start. Collectivly all my major machines add to 6500 watt requirement. What size generator will I need? Thank You. Jacbern

Jac,

If you were going to run all machines at the SAME time, you’ll need around 8-10K watts. Assuming some of your machines have motors or something that will require occasional surge watts. Smaller and you will be limited to what you can run at the same time. Make a list accordingly of your machines and when they’ll be running, and you might be able to save some on a smaller unit. Good luck.

Ray

hey m keyur,i am working on automobile water pump that power need 10Kw (13-15 Hp).

so which size of generator use? m working for wind operated kit.

I’m sorry Keyur. This answer is beyond my knowledge. Maybe one of our readers can help. Good luck.

Ray

Hello, if I need to run a medium sized deep freezer for about 10 hours, what size generator will I need to keep it running?

Hi Melissa,

Not knowing your amp requirements for you particular freezer, this is only a guess.

1000 – 1500 watts would probably suffice.

Check the information plate and see how many amps your freezer requires.

Multiply that by 120volts and that will give you the watts required.

Then add another 50% or so for surge watts. Especially if you plan to open and close the freezer often during this 10 hours.

Remember though, a freezer can keep its contents frozen for several hours with no power with the door closed.

So it will depend on the size of your freezer and why you need 10 hours of power, whether you need a generator at all.

Let me know if you need more information. There are alot of assumptions in my answer.

Ray

Guys if I need to power a steamer that is 1500 Watts..will a generator that is 1800 starting Watts and 1400 rated big enough to handle this?

Hi Ramon,

You will be better to get a larger unit. You may have trouble with it bogging down or shutting off. With a larger unit you will have a more versatile generator that can be used for other things that you may not be thinking of right now, but will be glad when you do. Good luck.

Ray

I’m considering a small portable microwave to take camping in my van & would then need a small portable generator if no electric service is available. Looking at microwaves that are 700w or 900w. What else must I know to be able to determine the generator requirement I’d also want to run a fan also, but not when the microwave is in use.

Thanks in advance for any assistance

Hi Sylvia,

You have important information in that your microwave is up to 900watts. This is the minimum number of watts that the appliance needs to operate. Please remember that certain appliances (those with motors) require more watts than their running watts when they start. The same will apply to your fan that you want to run. So figure that you’ll need a 1000 watt generator with 1200 surge watts.

The second thing you’ll want to consider is the noise, if you plan to use it camping. An inverter generator is the choice here if noise is an issue. They are a bit more expensive though.

Make sure that you operate your generator well away from your van. The Carbon Monoxide emitted can be deadly.

Be safe and have fun.

Ray

Hi, I’m writing a story, my scenario is I need a generator(poss an inverter type)to power a table top freezer (LEC5005W) 146kWH 32lt capacity, it has a ten hour power fail and will be disconnected from power to save on fuel, a couple of low wattage lights will be connected, also phone charge and may be some small kindle type tablet to entertain a youngster. Would a 1000 output be suitable or something larger, thinking my character will have the small freezer already up to running order before being plugged in initially. Thanks Jan

Remember a freezer is very efficient in keeping things frozen, when the door remains closed.

Should you open it, keep this to a minimum and your contents should remain frozen for several hours.

Over a 10 hour period, you will have to run a generator a couple of times to bring the internal temperature back to it’s prescribed temperature.

A 1000 watt generator will may not have enough output when the freezer needs it’s “surge” when starting.

If it’s just a story, use a larger 2000 watt generator.

Ray

Many thanks, it’s to be used in a converted horse box so a small one would be ideal, yes it’s just a story but I’d like it to be believable, Jan x

Hi Ray, I have a frigoglass chiller fv 400,368litres for my shop but my spg 3000 gen doesn’t seem to make it work. What kind of generator will I need for the chiller.

Tracy,

I assume that the chiller works and that the generator work. Simple assumption but important.

I’m not familiar with your chiller, but your shouldn’t need a certain “type” of generator, just enough output.

Check the amp requirement of your chiller and use the formula watts = volts times amps.

If Amps is 10 and your generator puts out 120 volts, then you would need 1200 watts from your generator to “run” the chiller.

Add another 50% for the cycling requirements and your 3000 watt generator should be enough.

Your frigoglass chiller probably needs more power.

Ray

Hi there, I am not sure if this is even possible, but I am wanting to cool a 10x20x8 ft pop up garage tent. First, I was wondering if this could be done with an 8000BTU portable air conditioning unit. Second, what size generator would i need to power this and would it be relatively quiet? Thanks. Let me know if I can provide any further information.

Hi Bill,

I’m assuming that the garage tent is fully enclosed? Are you going to have your AC in the tent, drawing air from outside?

It seems that this would not be well insulated and the cool will dissipate easily. That aside:

Find out how many Amps your unit needs. 10? If so you’ll need at least a 2000watt. But AC’s can fluctuate so the more power you can get the better.

You mention how quiet. The larger the unit, the noisier it will run. Consider a quieter inverter generator but it will cost more.

It should go without saying that the generator will be run away from the tent, right? The farther away, the less noise, but the farther away the more expensive cord you’ll need. Good luck.

Ray

Pls I need a generator that can carry my fridge and sump pump, though I won’t be putting them on at the same time, thanks

Hi Lydia,

If you only want to run these two items, but not at the same time you shouldn’t need a large generator. You’ll need to determine how many amps your items require. This will determine how much power you need to “run” them. However both of these require what is called “surge” watts as their motors start up. Take the higher number of amps required between the two. Multiply this by the amount of volts your generator will produce (probably 120). This will give you the MINIMUM amount of watts to run your appliance. Double this number to cover the surge and get a generator that can supply this amount of watts. Hope this helps.

Ray

What size generator do I need? I am attempting to DJ with 2 Alto 800watt peak power Speakers (400 continuous) with a small Wego 3 Pioneer DJ controller and Apple Laptop. Will a 2000watt Generator/Inverter be enough?

Hi Jeff,

Without knowing the amp requirements of all you want to do, it is difficult to know if this will be enough. Make sure, that even with an inverter generator, to protect your laptop when operating from this generator with the other things running at the same time.

Ray

Pls, can 1.8kva generator power a 24 inch LED tv,a mini home theatre, ceiling fan, standing fan and a table height fridge?

you’ll need to add up your amp draw for all of these items and if you plan to run them all at the SAME time, see if you have enough running watts by the formula watts equals amps times volts. So if you have a 120volt generator, multiply with total amps, say 20 amps, then you need 2400 watts just to run them. With their surge requirements you’ll need about 50% more. By this example, 1800 watts will not be enough. Hope this helps.

Ray

So, I have a small air compressor. The manual doesn’t say much. 120V, 60 hertz, 10 amps. Now I’m

Ordering a Honda EU1000i that has a max output of 8.5 amps at 1000 watts. Will this run the compressor?

Hi Brian,

That might be a bit undersized. Your 1000watt Honda probably runs at 800watts.

If your item runs at 10amps, you need 1200 watts just to run it, not counting the surge watts that it will require on startup.

You’d be better off with the 2000 watt Honda although it will cost a bit more.

Ray

I need to purchase a portable generator as opposed to a heavier standard. I need to run a 5000 btu A/C for my camper and that’s it. Do you think a 2200 start up 1700 run watts portable generator will do the trick?

John, it sounds like you should have enough if your unit needs 5 Amps or so. Check with your A/C maker to make sure.

Ray

Ray,

I have a 1500 Watt, Lion Energy Fuel-Less generator. I am thinking about an induction cooking plate. It is labeled as 1500 watt. Can the generator handle it or do I need to purchase something else?

I understand that I would be maxing out the generator, but I have 3 solar panels at this time. Want to use it for camping or survival.

Hi Sharon,

You don’t want to rely on running your energy providing device expecting it’s full output. It may fluctuate below what you expect. If it is survival you’re worried about, don’t leave it to chance or without testing fully before you need it.

Ray

Ray,

Can I damage the generator by trying the 1500 Watt cook stove or could it possibly damage the cook stove? How would I know that it is OK?

It is an induction plate. Spoke with the company and asked them to consider a slightly lower Wattage and they seemed interested. Time will tell.

Hi Sharon,

If the generator bogs down or shuts off due to too much load, it is not good for the generator repeatedly. As far as you induction plate, I can’t see how trying to operate at less than its requirement may damage it. I suggest looking at its manual or contacting the maker again. As a rule of thumb I always recommend a larger generator capacity that you expect to need. No one ever said, “I wish I had less power”.

Ray

Hello…

I have 1500 watts mitsubishi generator. Can it handle a deep freezer 400 watts and a light bulb 20 watts. Seeing you table, a deep freezer 400 watts needs 400 surges watts as well. What is the correct size watts from a generator i need to buy?

Thank you.

The table are estimates only. But from what you tell me 1500 watts should be enough to run your 400 watt freezer and a light bulb, even with the surge requirement of the freezer. Remember, the freezer does not need to be run continuously in an emergency. With the door closed it acts like an ice chest, keeping things cold. You can use your generator for other purposes periodically. But you have to be diligent in your timing.

Ray

Will a 1500/1800 regular generator run a 5000 BTU A/C and handle the start up. 4 amps I believe

This is the lower range that “could” work. It is recommended to go with a 2000watt generator or larger.

If you already have the generator see if it will operate under working conditions. If not, get a larger generator, the extra watts won’t cost much more.

Ray

There certain times during the year that I need to power my sump pump during power outages, not many times but enough to create a lot of concern. I have a Zoeller pump which operates at 9.6 amps (1152 watts) with a surge start up of 25.9 amps (3108 watts). I am looking for an inverter generator that would provide the power needed to run my sump when needed but would also provide power for other recreational activities (tailgating, camping, computing, TV, etc) and be easily portable. Using the 80% rule for power usage it looks like I would need a generator with a running output of 1500 watts minimum and 4000 watts max power. Am I in the ball park with those numbers?

Ideally a generator like the Honda EU2000i/EU2000ic hooked up in parallel or the comparable Yamaha package would meet my portability needs. The Honda in parallel provides 3200 watts (26.6 amps) running and 4000 watts (33.4 amps). This seems to meet my sump power requirements, but I’m not sure if the parallel configuration is capable of providing the power. Any thoughts would be greatly appreciated.

Thanks

You’ve put a lot of thought into this. Sounds like you ran the numbers right. Yes there is a slight loss of power when you run tandem, but it you have excess, you should be ok. Good idea for the tandem where you can use only one for your lighter needs. Good luck. That’s a bit of an expense but you’ll get proven reliability.

Ray

Omg this is so confusing why can’t they make it more simple? For instance i want to run the most items but not the whole house. So a refrigerator, a 14000 portable air conditioner, and a tv . Now let’s make it simple and have a regular size refrigerator a 46 inch tv and the portable ac. What’s the biggest one I need to run them all together?

Simple answer. 5000 watt model should take care of these all at the same time.

If I have a 1200 running watt generator, can I run a 7000-8000BTU portable air conditioner?

Hi Veronica,

Your unit may be a bit underpowered for this size A/C. Primarily because an A/C has to use extra power when it surges or cycles on and off. You would probably be at or very near the limit due to this uncertain requirement which can be hard to determine. It would be a shame to expect it to work and when it comes time, it doesn’t or shuts off.

Ray

Hi Ray, I will be buying a generator and a mini split ac/heater unit 12k btu’s in the near futureto put in my truck. The ac unit says it consumes at 120V 11.9 amps, that’s 1428 watts. I’ve been told that to keep the ac running I would need a generator that has a running wattage of 3X thst of the ac, now i don’t think that’s right especially by what I’ve been reading above. When the compressor kicks in it needs around 1.5 additional watts from its normal running wattage, that would mean I would need an additional 2142 watts more while running making it a total of 3570 running watts for the ac to stay running. Let me know if this is right or not, I was planning on buying the 4k/3.5k surge watts champion generator, but with this in mind i think that will not be enough. I also plan on hooking up while I’m on my 10 hr break my small refrigerator which consumes maybe like 300 or 400 watts and a 700 watt microwave. What size generator would i need for this? Thank you in advance for your feedback.

Those who recommend that much surge wattage are generalists who “know” that more power will be used that the minimum mentioned due to powering more items such as your wish to power your refrigerator and microwave. Your 4000w surge will probably take care of your AC needs, but you will never regret buying more watts than you think you’ll need. A generator is a several year investment, and who of us can see our needs years into the future. Good luck.

Ray

Hi have just brought a2000w pure sine wave generator will it have enough power to run the hair straighteners

Hi Martin,

Whether your generator has enough power depends on the “hair straighteners” that you are referring to. If they are simply a flat iron, then possibly so. As you know blow dryers can use a lot of power. A 1600 watt blow dryer may not work when you turn it on due to extra surge watts needed.

Ray

I have a machine which is rated like 1500 w 2 hp 240 v…

To run that machine what capacity generator i need??

Please guide me

Your machine with a motor requires an amount of surge watts which can vary depending on what your machine is. The most logical way to go in my thinking with this information is to take into consideration that it also requires 240V. That will determine in part the power output of your generator. You might consider a 4000 – 5000 watt model with 240V capability. Make sure that you consider your outlets on your generator and your machine. Hope that helps.

Ray

Hi Ray

I am setting up an ice cream van in an RV and will be using a separate freezer when operating, (120 volt)

What size of generator would you recommend?

Thanks

Hi Howard,

To run just a freezer, it shouldn’t take that large of a generator. You’ll need to know the amp draw of your freezer. Then multiply that number by the volts to get the amount of watts you’ll need to run it. The double that number for surge requirements and you should be OK.

For example 10 amps time 120 volts equals 1200 watts. Double that and you get 2400 watts as your requirement.

Remember, get as many watts as you can afford. You’ll find a use for them someday. Consider an inverter generator if noise will be a factor.

Good luck,

Ray

Thanks for your detailed response.

Could you explain what this is and how they work?

Consider an inverter generator if noise will be a factor.

Howard

If you plan to use the generator in close proximity, inverter generators run more quiet than standard generators. This is mostly because inverter generators can “power down” if not in full use, whereas standard generators always run constant. You’ll notice that both however will increase in noise when more power is asked of it. Inverter generators are also enclosed in a housing which dampens the sound.

Ray

why will a 2000watts inverter not carry pumping machine 1.5hp but 2000watts gas generator does, afterall same rating

both should work if one or the other does.

Please, i’d like to knw what generator power i’ll need to run a split A/C unit of 1hp, 9000btu/h. Thanks

get 5000Watts which should be more than enough. Unless you’re asking for the least you can get away with, then you’ll want to look into the variable amp draw of your A/C unit.

Ray

Hello im trying to figure out which generator i would need for my project. Im wanting to run a small window unit, mini fridge and microwave, and Tv. As well as charge electronic devices. In other words im going to be living in a converted rv for a while. Will a 3000 watt inverted generator r do this for days at a time?

Hi Ty,

Remember you will not be running each of these mentioned at the same time. You can figure that when you use your microwave, you can turn off your TV or unplug your mini fridge (just remember to plug it back in). The A/C (is that what you’re calling “small window unit”?) may run on 3000 watts depending on the Amps required. So the short answer is probably yes. But you’ll want to investigate further before you make the investment, because it’s not a small investment.

Ray

I have a smart meter Texas account and am able to see “actual” KW usage in my home for previous days (not the current day), months, etc.. I can sort my electricity usage by monthly, daily, and in 15 min. intervals.

My question is:- If my peak running watt usage in KW for a 15 min. time frame is about 1.8 KW. Do I just multiple this number by 4 to get my usage for a KW/h (e.g. 1.8 KW x 4 is 7.2 KW/H ?

The reason I’m asking is because I’m trying to size a portable generator and I want to ensure I have one that will run this load easily (e.g. about half the rated load).

So here is my thinking. Do I buy a generator that rated for 12,000 watts with a 1/2 load running watts of about 6500 watts? or will I need a bigger or smaller generator?

I just get confused with the “ratings posted by generator labels.” Is the listed ratting of 6500 running watts for a single moment in time or per hour?

Hi Michael.

Yes the ratings are for the generator output at any given time.

12,000 watts seems like more than you need for that amount of usage.

Also, during emergency situations, one would rarely use as much power as during non-emergencies as you would normally cut back.

Add up the total usage that you expect to use the generator for and double and triple check this need.

You may find that you can get away with a smaller choice generator.

But you are wise to not expect to tax your generator to full load.

Double check with a electrician before you make your final call.

Ray

Hi,

I can’t seem to get a consistent answer on my needs for a whole house generator. I plan on building appx 2400 sq ft home. I’ll have natural gas for stove, water heater.

I’ve looked at my current electric bills for the home we live in now which is appx the same size. At the most per 12 months of electric use came down to 1800 kw per month which averages out to be 2.34 kw for 32 days. I also went out and looked at my breaker box and added up the total amps for 455.

I’m so darn confused. Any time I speak to someone they only add more confusion about what is needed. So my question is this: all things being equal is there a way to figure my needs? I’ve figured different ways and have come out from 12,000 to a 24,000 unit. That’s a huge difference. HELP! Thanks

Hi Carla, yes it can be confusing.

First question for you, are you planning to live off the grid with the generator being your sole source of electricity?

Or are you planning for when there is a power emergency and you are without power for a length of time?

If the answer is living in a cabin in the woods with no source of electricity, then I don’t feel that I can help you.

But if you need temporary power, then there are some basic considerations.

You’ve done your homework well.

Your breaker box in your new home will be sufficient to run your home.

But in a power emergency, you don’t run everything the same way you would during good times.

For example if you had 50 light bulbs, they aren’t all on at the same time as your TV, stereo, A/C, microwave, refrigerator, etc.

So you don’t have to consider all 50 light bulbs.

Go through your home and look at all the necessities that COULD or SHOULD be on at the same time.

Refrigerator, freezer, sump pump, whatever. Most power needs in your home are not continuous.

If each light bulb was 100 watts, if they were all on at the same time, you would need alot of power.

But use them one or two at a time and your needs are much less.

You could turn off your TV when you want to use your microwave.

Make sense?

So list your power needs as “must haves” and then your “nice to have” and then your “don’t need”

Add up their power requirements with what is comfortable for you and get a ballpark answer.

Your estimate of 12000 watts is probably enough.

Ray

I have a 1.5hp compressor and i am looking to buy a Gentrax GT4000 GENERATOR.

It is 1700w/max – 1400w/rate. Would this generator do the job.

It may be a bit on the small side, Rob. Especially with the startup requirements of the compressor. If you haven’t purchased the generator yet, get a larger one. Not that much more to get 3000W.

Ray

Wow!! When you’re not dancing, you’re giving such great information.LOL

I read everything and have been educated and entertained. Now if I can just remember the formula volts x amps / watts = what?

Thank you. Shelly

Thank you for the kind words Shelly.

Ray

I need a quiet generator for 40″ smart TV and a ps3 game system need assistance on what to buy and at a reasonable price. And easy storage for my truck. I drive 18 wheelers

Hi William,

As far as quiet, most inverters don’t vary much in noise. Cost though, now there’s a difference. Check out the Yamaha for the higher end and the Earthquake on a lower end. Both reviewed on this site. But your TV and game system don’t need that much power to run. Are you planning to use the generator in your 10 wheeler while on the road? Meaning you’ll set up the generator some distance from your cab and let it run?

You might consider a solar generator which will store enough power to run your tv and gaming system when you use it. AND it will be silent operation.

Hope this helps,

Ray

Ray, you are one of a kind! A boon to people who is a novice on portable generators, like me.

Now following your formula, I have a 25 cubic ft of refrigerator, with a wattage of 826.85, and a compact freezer of 194.35 watts for a total of 1021 watts, would an inverter generator with 2000 watts max output, should be plenty enough, that I can also run a PC, and a radio maybe alternately?

I saw an inventer generator that’s also portable costing as much as half the cost of Honda and Yamaha for only a little bit over $500. It’s brand name is Wen . Have you heard about it? What do you think, since I will only be using it for emergency back up, that may happen maybe every 3 or 5 yrs, or not at all.

Kudos to you for your knowledgeable and helpful advice. More power to you!

Leo Degamo

Hi Eligio,

Yes, 2000 watts is enough for your example. And YES you can find less expensive brands with near equal consumer satisfaction. Yes WEN is a good company. You might also look into Champion (you’ll find a review on this site). An emergency generator is good to have, but we hope you’ll never need it for an emergency. The are however VERY handy to have around even in a non-emergency situation. Just don’t let your friends know you have one. They’ll be borrowing it all the time.

Ray

Hi Ray,

I need to power 3 X 12,000 BTU split units (air conditioners)

1 refrigerator and 1 deep freezer, with some lights and 1 television.

I am planning to buy 13 KVA generator that will give me 25 amps.

Will this be enough?

Thanks

That’s a good size unit Alvin. Should be enough. It will be rare when you are running EVERYTHING at the same time. But still you may find you have a bit left over. The AC units won’t all surge at the same time.

Ray

hi Ray

I have 1 fridge orient 2 tv “14” inch 1 pc with 17 inch lcd.1 hp 4100 laserjet printer 3 fans on the roof 6 sever and 1 water pump 1 hp how many watt generator are required

sms

Hi SMS,

It depends on how many amps your list will draw. I also depends if all the items that you mention will be run at the same time.

Your fridge will probably draw the most if it is a normal size. Look on the plate on the back to see how many amps it needs to run. Next is your water pump. You can always unplug your fridge when you run your pump if not needed all the time. For your computer, you might want to consider an inverter generator to keep your electronics safe. Are your fans on the roof, standard ceiling fans? Do you need to run them all at the same time?

I’m sorry I can’t be more help. The first thing you need to do is look for the power draw on each and add them up, and if you need to run them together.

Ray

Hi,

I just purchased a 4000 watt generator just to get me by for the winter for some lighting in my warehouse. I only hooked up three 75 watt clamp lights and they do not power on.

I can run my angle grinder and my jigsaw with no problem.

What would cause the lights to not work?

I tried a 40 watt bulb and that powered on but seemed to be pretty dim.

Thanks In Advance,

Josh

You might have a problem with the outlets. When running the power tools, is it from the same outlet?

Hello,

I have a commercial Kalvinator 18 ft Freezer and 18 ft Refrigerator, they both are 115 Volts with 5 Amps start up each for a total of 10 Amps. Run Amps is 2.3 each. I did the calculation of both for a total of 1200 watts. Would a 2000 watt inverter portable generator operate both appliances? Thanks

Your calculations seem correct Kevin. Just make sure of the running watts of your 2000 watt generator. The rating of 2000 is usually the surge watts.

Ray

I am configuring a food truck that has total wattage of all appliances 11.3Kw calculated at approx 95 amps. I am considering a 14.KW generator that only has 50A plug. My question is how do I get enough power to my truck with 1 50A plug/cable or am I missing something. Please help me to understand.

#ScratchingMyHead

Hi James, your requirements assume that you will be using ALL appliances at the same time. Typically 50Amp generators would be sufficient under most circumstances. Calculate your best estimation of what will always be running (including surge watts). Periodic usage of other appliances can make up the difference. Good luck.

Ray

I need to power 4 heating elements at 8 amps each. I cannot use a generator because it needs to be indoors. Is there a way to generate the power needed without using a gas generator? It is needed in a hotel room situation.

Hi Nick,

Do you need the power continuously or periodically. You might consider a battery bank that you can keep charged through solar? It’s an expensive option.

Ray

Hurricane season is approaching. During One we were without power for 10 days. We have a special generator plug hooked up to our electrical panel. We’d like to run the downstairs a/C unit, some lights, the refrigerator, and occasionally the oven or stove. What size generator should we buy?

Hi Deb,

Remember, when determining what size generator to get for emergencies:

1. You don’t run everything at the same time.

2. You’ll be happier with more power than less.

That said, The A/C if around 12,000 BTU’s (standard window type) will require about 1,200 watts. Your refrigerator about the same (when you consider surge watts). Your oven (size dependent) may take as many as the others.

Remember you can unplug the refrigerator when you use the stove, and it will remain cool for hours. Just remember to plug it in again.

So a 4000 o 5000 watt generator could be enough.

If you have a built in plug, determine what type of plug it is and it will partially tell you what size generator will best work with it. 20Amp, 30Amp, 50Amp.

Also note that a built in plug will probably already be designed to take the power to certain areas of the home.

If you plan to use that plug, check with someone who can read your electrical box and test before you rely on it.

Good luck,

Get ready, but don’t need it.

Ray

Thanks!!!

I have a 2000 watt generac that I want to know what size portable room a.c. I can run off of it. Very important I travel with pets and they need air in the back of the van!!

Hi Michelle, a standard 12,000 BTU air conditioner that will cool a 400-500 sq. ft. room takes about 1,000 to 1,2000 watts. To cool the back of a van is much smaller than 400 sq. ft. Please remember to keep the generator far away from any enclosed space. Good luck.

Ray