What Size Generator Do I Need For My House?

Last Updated on July 4, 2022

In case you don’t know your appliance’s actual load capacity, you can use a general rule of thumb to determine this. The regular fridge needs about 600 watts to start. It needs 180 watts to run. Slow cookers, on their part, need 170 to 270 watts for both starting and running. A 650 watt microwave requires 1,000 watts right from start to finish.

A smaller flat TV requires only 120 to 200 watts. Keep in mind that most smart TVs draw reasonable power, even when switched off. This enables them to restart automatically. Satellite receivers require some 250 watts continually, just like generator-powered laptop computers. A radiant heater packs in about 1,300 watts while starting and when running continuously.

Estimated Appliance Wattage Chart


ApplianceRunning WattsStarting Watts
Curling Iron1,500 W1,500 W
Electric Shaver15 W20 W
Extractor Fan12 W13 W
Hair Dryer1,250 W1,250 W
Power Shower7,500 W10,500 W
Straightening Iron75 W300 W


ApplianceRunning WattsStarting Watts
Air Purifier30 W40 W
Robotic Vacuum Home Stand30 W90 W
Steam Cleaner1,000 W1,800 W
Vacuum Cleaner1,000 W1,500 W

Construction Tools

ApplianceRunning WattsStarting Watts
Air Compressor (1/2 HP)1,000 W2,000 W
Air Compressor (1/4 HP)970 W1,600 W
Air Compressor (1 HP)1,600 W4,500 W
Air Compressor (2 HP)2,800 W7,700 W
Airless Sprayer (1/3 HP)600 W1,200 W
Angle Grinder900 W1,500 W
Belt Sander1,200 W2,400 W
Bench Grinder1,400 W2,500 W
Chainsaw (14”)1,200 W2,400 W
Circular Saw (7.25")1,400 W2,300 W
Concrete Vibrator (1 HP)1,100 W2,500 W
Concrete Vibrator (2 HP)1,800 W3,600 W
Electric Drain Cleaner250 W250 W
Electric Drill600 W900 W
Hammer Drill1,000 W3,000 W
High-Pressure Washer (1 HP)1,200 W3,600 W
Impact Wrench (1")1,200 W1,400 W
Jig Saw300 W700 W
Jointer/Planer1,800 W4,500 W
Miter Saw (10")1,800 W3,300 W
Orbital Sander600 W1,200 W
Reciprocating Saw960 W1,040 W
Shop Vac (6.5 HP / 14 Gal.)1,000 W1,500 W
Table Saw (10")1,800 W4,500 W
Welder (Electric)2,000 W2,500 W
Wood Router600 W1,500 W


ApplianceRunning WattsStarting Watts
Amazon Echo3 W3 W
Amplifier300 W300 W
Apple TV3 W3 W
AV Receiver450 W450 W
Blu Ray Player25 W25 W
Cell Phone25 W25 W
Computer Monitor25 W25 W
Desktop Computer100 W350 W
Home Phone3 W5 W
Home Sound System95 W95 W
Laptop60 W60 W
Mi Box5 W5 W
Nintendo Wii15 W15 W
Playstation 4165 W165 W
Playstation 5340 W340 W
Set Top Box27 W27 W
Soundbar30 W30 W
Stereo450 W450 W
Tablet10 W10 W
Television (CRT)500 W500 W
TV (43" LED)80 W80 W
TV (55" LED)90 W90 W
TV (65" LED)100 W100 W
TV (75" LED)115 W115 W
VCR / DVD Player100 W100 W
Video Game System40 W40 W
WiFi Router5 W15 W
Xbox 360160 W160 W
Xbox Series X200 W200 W


ApplianceRunning WattsStarting Watts
Cultivator (1/3 HP)700 W1,400 W
Electric Leaf Blower (Handheld)750 W1,440 W
Electric Lawn Mower900 W1,500 W
Electric Strimmer300 W500 W
Hedge Trimmer600 W1,500 W
Weed Cutter500 W600 W


ApplianceRunning WattsStarting Watts
Air Fryer1,500 W0 W
Blender500 W800 W
Chest Freezer450 W900 W
Coffee Maker750 W1,200 W
Crock Pot250 W250 W
Deep Freezer500 W1,500 W
Dishwasher1,500 W1,800 W
Electric Grill1,650 W1,650 W
Electric Kettle1,200 W3,000 W
Electric Oven2,150 W2,150 W
Electric Skillet1,500 W1,500 W
Electric Stove (8" Element)2,100 W2,100 W
Espresso Coffee Machine900 W1,500 W
Food Dehydrator800 W800 W
Food Processor400 W400 W
Garbage Disposal450 W1,600 W
Hot Water Dispenser150 W750 W
Induction Cooktop (Per Hob)1,200 W1,800 W
Microwave (1000 W)1,000 W1,000 W
Modern Fridge400 W600 W
Pressure Cooker700 W700 W
Range Hood65 W65 W
Refrigerator700 W2,200 W
Rice Cooker200 W500 W
Sandwich Maker700 W700 W
Slow Cooker160 W160 W
Smart Fridge500 W750 W
Steriliser650 W650 W
Toaster850 W850 W
Toaster Oven1,200 W1,200 W
Waffle Iron1,200 W1,725 W
Water Cooler80 W80 W
Water Dispenser100 W100 W
Wine Cooler (18 Bottles)83 W83 W


ApplianceRunning WattsStarting Watts
Light Bulb (Common)75 W75 W
Light Bulb (LED)9 W9 W
Night Light1 W1 W
Outdoor Light String250 W250 W
Tube Light (1500 MM)25 W25 W


ApplianceRunning WattsStarting Watts
Clothes Dryer (Electric)5,400 W6,750 W
Clothes Dryer (Gas)700 W1,800 W
Clothes Iron1,200 W1,200 W
Steam Iron350 W1,200 W
Washing Machine1,150 W2,250 W


ApplianceRunning WattsStarting Watts
Copy Machine1,600 W1,600 W
Fax70 W70 W
Paper Shredder200 W220 W
Printer (Inkjet)30 W50 W
Printer (Laser)300 W550 W
Projector220 W270 W
Scanner10 W18 W


ApplianceRunning WattsStarting Watts
Sump Pump (1/2 HP)1,050 W2,150 W
Sump Pump (1/3 HP)800 W1,300 W
Well Water Pump (1/2 HP)1,000 W2,100 W
Well Water Pump (1/3 HP)750 W1,600 W

RV Camping Essentials

ApplianceRunning WattsStarting Watts
AM/FM Radio100 W100 W
Box Fan200 W200 W
Coffee Pot550 W900 W
Electric Water Heater (6 Gal.)1,440 W1,440 W
Furnace Fan (1/3 HP)700 W1,400 W
Hot Plate1,200 W1,725 W
Inflator Pump50 W150 W
LED Lights5.6 W5.6 W
Microwave (650 W)650 W650 W
Mini Fridge100 W200 W
RV Rooftop AC (11,000 BTU)1,000 W2,100 W
RV Rooftop AC (13,500 BTU)1,400 W2,900 W
RV Rooftop AC (15,000 BTU)1,700 W3,500 W
Space Heater1,800 W1,800 W
TV (32" LED)50 W50 W

Heating and Cooling

ApplianceRunning WattsStarting Watts
Ceiling Fan75 W120 W
Central AC (24,000 BTU / 2 Ton)2,800 W8,600 W
Central AC (30,000 BTU / 2.5 Ton)3,600 W10,800 W
Dehumidifier300 W300 W
Electric Heater (Fan)1,500 W1,500 W
Electric Thermal Radiator500 W500 W
Electric Water Heater4,000 W4,000 W
Electric Water Heater (Immersion)3,000 W3,000 W
Electric Water Heater (Tankless)6,600 W6,600 W
Evaporative AC700 W700 W
Fan (Pedestal)50 W50 W
Fan (Table)30 W30 W
Fan (Wall)55 W55 W
Furnace Blower (1/2 HP)850 W2,350 W
Furnace Blower (1/3 HP)700 W1,400 W
Heat Pump (3 Ton)5,400 W7,200 W
Humidifier (13 Gallon)175 W176 W
Portable AC (5,000 BTU)600 W1,800 W
Window AC (8,000 BTU)960 W2,800 W
Window AC (10,000 BTU)1,200 W3,600 W
Mini-Split AC (12,000 BTU)1,500 W4,500 W
Mini-Split AC (18,000 BTU)2,200 W6,500 W

RV energy Hogs

Air conditioners are considered as the energy hogs of the standard RV. A 7,000 BTU rooftop RV AC requires around 1,700 watts starting and 600 running watts. A larger, 10,000 w BTU RV AC needs some 2,000 watts starting and 700 watts running. After adding up the starting and running wattage of the baseload, you will get how much power your generator requires.

Using an example of a smaller AC, microwave, fridge, and TV, the starting load would be about 3,420 watts, if you switched them all at once. The running load will be some 2,000 watts. This does not, however, take the light bulb load into account. So, if you want to run an air conditioner and several essential home appliances simultaneously, you need a generator with a capacity of, at least, 3,000 starting watts and 2,000 running watts.

How to Determine Appliance Power Requirements

You will discover that most electric motors and appliances usually list their power requirements in the form of amps. Some typical locations include The nameplate, a bottom-side stamp, or a data tag placed on all electric motors.

electric motor data tag


Appliances with electric motors generally need some additional start-up power. This may be up to 3 times the running amount.

Note that older appliances might require more power than indicated since, over time, they become less efficient.

Use a tester for appliance load to determine the precise power of regular home appliances and tools.

Calculating Watts and Kilowatts

Power is defined as the amount of work done in a given time. The term watts refers to the unit used to express power. Indeed, watts is a typical function of current and voltage.

To calculate the quantity of electric power, you should multiply the amperes by voltage. Thus, you will obtain what is referred to as watt-hours. Moreover, Kilowatt-hours is another common unit. Kilowatt-hours is basically determined by the number of watts divided by 1,000. Further, one kilowatt equals 1,000 watts. By this measure, if you divide 1,500 Watts by 1,000, the result is 1.5 Kilowatts.

Power Surge

Generators are commonly rated in Watts or Kilowatts. This expresses the amount of work they are capable of doing.  Similarly, an athlete can burst out in explosive, sprinting energy for some seconds, a generator can do something comparable, mustering a surge of extra power within seconds. This kind of added capacity allows the generator to ignite electric motors. Typically, it takes an initial power boost to start turning.

The above example shows the relationship existing between volts, watts, and amps, and also why watts or kilowatts (rather than amps and volts) are used to rate a generator’s power.

Types of Loads

Some appliances generally require more power to start up. Others usually maintain constant power. If you want to calculate your power needs correctly, you should know the kind of loads you wish to run. A load is generally defined as the device that requires power.

There are two main kinds of loads:

Resistive loads

Resistive loads are simple. They typically use the same power capacity to start and run appliances. Most resistive loads are used in heating. Here are a few examples of resistive loads: Toasters, Coffee makers, Light bulbs.

Reactive Loads

Reactive loads usually contain an electric motor. This requires extra power to start. However, it uses less power once it starts running. The starting power is about three times the power capacity needed to run regular applications. Here are some examples of reactive loads are: Furnace fans, air conditioners, well pumps, air compressors, power tools, and bench grinders.

Some household appliances, for instance, the furnace or refrigerator, come with intermittent internal fans. Generally, some extra wattage/power is required to start the fan every time. Moreover, refrigerators have a defrost cycle. This also requires energy, not to mention the fans and the compressor.

Further, reactive loads may require extra power as soon as the electric motor starts to work. For instance, when a saw starts cutting wood, its power requirement generally increases. This, however, does not apply to most household appliances.

What Size of Generator Will Run All Appliances at Home?

You are probably fed up with the ordeal of being left in the dark every time a power outage happens. Most likely, you are searching for a suitable home generator that can help you deal with this issue once for all. How will you know which is the best type of generator to purchase? How can you get a machine that will run your home and keep you protected during emergencies?

Here is how to determine the best generator size for your needs:

Find out the facts about the starting wattage for the generator you want to buy. This means you need to know the surge wattage of the appliances at home and the fixtures you wish to power.

Pick a generator that has enough power capacity to exceed the combined wattage of all appliances that you plan to power. In time, we will let you know exactly how to do this. In the meantime, it would be interesting to answer this question first: How are generators typically sized?

Which Heaters Do You Use?

Also, what kind of water heater do you use? Is your heater electric, oil-fired, or gas-powered? You should know that oil or gas-fired water- heaters generally require less power. They can work with as little as 2,500 watts.

On their part, electric heaters usually require no less than 4,500 watts to work. Most householders generally power a variety of household gadgets and appliances, with about 3,000 to 6,500 watts of power.

In case your home uses a smaller furnace or city water, you should still expect to use between 3,000-5,000 watts. This should ordinarily cover your needs. If you have a larger furnace or well- pump, you will, most likely, need a generator with a capacity of 5,000 to 6,500 watts.

Generators for Power Outages

There are those who, unfortunately, have to deal with the challenge of frequent power outages where they live. Sometimes things get worse, and these outages happen frequently and are prolonged.

If you stay in an area that is prone to the vagaries of severe weather characterized by ice storms, blizzards, hurricanes, and other hazards, the situation can be worse. In such cases, before buying any generator, think twice.

Particular types of generators will do well in these situations.

Consider buying the following types of generators:

  • Large inverter.
  • Home standby.

These three types of generators are usually packed with enough power capacity to run the entire household. They can be directly connected to the circuit breaker panel at home. Moreover, they will allow you to control and run hardwired appliances. These include air conditioning, central heating, sump pumps, electric ranges, well pumps, and water heaters.

In case you have these at home, and you think it necessary to have them running during power outages, make sure you install a transfer switch at your breaker box. Get a licensed electrician to do that.

Generators for Occasional Outages

Other people live in areas where occasional power outages happen. At times these are sustained. Regardless, you would not wish to spend a fortune buying a standby home generator.

In such cases, consider buying the following suitable types of generators:

  • Large inverter generator.
  • Portable generator.

Unless you experience frequent power outages each year, it may not be prudent to spend $10,000 or more as the cost of buying and installing a stationary unit. You could, instead, save much money if you are willing to pull your large portable or inverter generator out of a shed or garage, hooking it up during power outages. Even so, it is advisable to install a transfer switch in such situations.

Rare Lack of Power

Anything can still happen even if you are fortunate enough to have reliable running power. These are human processes that cannot be 100% perfect. Have a standby generator at home to stay safe. You will have more peace of mind.

Consider buying either a recreational inverter generator or a midsized inverter generator. The latter machine will give you enough power to run a window A/C, space heater, or a fridge.

Indeed, machines like recreational generators are compact items that are easy to carry wherever you go. You can even use it to run your TV and cooktop at a wild tailgate.

How Do You Measure Regular Generator Power?

In simple terms, generators are usually sized based on their electric output capacity. They are not sized considering the physical dimensions or characteristics.

The power output of a generator is usually measured in Kilowatts (kW) or watts (W). Both of these are common measurements applied to electricity. Generally speaking, 1kW= 1,000W.

Of course, whenever you plan to purchase a generator, make sure you go for the right-size of a generator.  Why is this wise?

Avoid Overloading the Generator

If you have a generator that is too small for your power needs, you are likely to overload the machine. Otherwise, you may also find yourself forcing a smaller generator to supply more power than it was designed to do.

If this happens, the generator will automatically shut off or get overheated. Not only would this endanger the life of your generator, but you will also put your valued appliances at the risk of damage.

What happens if you purchase a generator that is too big, in terms of power capacity?

Buying an Oversize Suit?

In that case, you will be overpaying to buy a machine that you don’t really need. You will spend much on the generator unit and spend even more on the operation costs of a device that is grossly underworked.

To illustrate, you will be like a man who buys an expensive, oversized suit that he would never wear for social functions. Yet the outfit needs regular maintenance, at high costs, in the laundry.

How, then, can you accurately calculate the right generator size to satisfy all your domestic power needs?


There is no doubt that electricity has completely changed the world. As man’s reliance on electricity grows, so does the impact of electricity in our lives. Yes, this power is what keeps our homes safe, warm, dry, and powers a variety of tools and appliances, making our lives easier.

Learn the terms associated with this peculiar phenomenon, how to calculate generator power, and, ultimately, how to pick the best generator for your needs. Life will, likely, become much better.

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