What Size Generator Do I Need For My House? (Chart Included)

An average size home requires from 5000 to 7000 watts to power essential items like refrigerators, AC, Lights, Fan, PDA (laptop, mobile, etc.), FM Radio, TV, Food Processor, Blender, Washing Machine, Sump Pump, Space Heater, and others. Please remember you can not run all the appliances at a time if the summation of the appliance’s power is higher than the Generator Power. 

The size of the generator depends on your demand. If you are living off-grid you need a powerful generator to power up all your necessary electrical appliances. 

On the other hand, if you are looking for a generator for use during a power outage, you don’t need a whole house generator. In this case, portable generators are enough to power your home appliances for a specific period. 

Which points should I consider before selecting a Generator?

To finalize the size of your generator, you should consider a few things. Let’s have a look at the points. 

Are you on Offgrid or under the regular electricity connection? 

Well, first thing first. Living in an off-grid farmhouse means you are self-dependent. In this case, solar power is more sustainable and cost-efficient rather than fossil fuel generators. However, you could consider the whole house or standby generators if you prefer generators to solar power. 

On the other hand, if you are under regular electricity and looking for a generator for emergency use or for outing purposes like camping, fishing, etc, then the portable inverter generator is the best choice. 

Based on running the sensitive electronics, generators are mainly 2 types. 

  • Inverter generator 
  • Non inverter generator

Inverter generators are safe to run every type of appliance including sensitive electronics like mobile, laptop charging, camera gear charging, etc. They are a bit more expensive than the portable non-inverter generator. But they produce low noise and offer more features than the regular generator. 

Non Inverter generators are less expensive than inverter generators. You will get up to 2000 watts to the 12000-watt portable generators on the market. Non-inverter generators don’t produce a pure sine wave. So, they are not perfect for running sensitive electronics. 

Based on the Fuel, generators are 3 types. 

  • Propane generator 
  • Gasoline generator 
  • Dual fuel generator

Propane generators are more convenient than gasoline generators for long use. If you need alternative power regularly for different types of DIY work, then you could consider the propane generators. 

Gasoline generators are also good. Basically, there is no basic difference between these two. If you have enough supply of gasoline you could consider the gasoline generator. 

Dual fuel generators are for smart people. Yes, they are a bit more costly than the other two types as you get more options here. If you have no budget issue, you could consider dual fuel generators. 

Identifying the essential and optional appliances during the power outage 

What is the primary purpose of using the generators at your home? Do you want to run all the home appliances including the heater, Air conditioner, and other heavy electronics? 

Or you just want to run the basic appliances during the power outage. 

Actually, the power consumption varies from user to user. A 3-member family doesn’t consume the same amount as a 4 or 5 members family. The math is super simple. Also, every family doesn’t use the same types of electronics. 

things to consider before finilazing the generaor size for your home

How long will you power Up your appliances with a generator? 

Another important topic that you should consider before buying a generator. Because you can not run a small portable generator all day long. It will definitely show a mechanical error when it can not handle the demand. 

The small portable generator is designed for running for less than 10-12 hours continuously. The time varies from brand to brand. 

So, you should finalize the demand initially. 

How much electricity actually do you need? 

So, you should count the wattage of your electronics. Every electronics appliance comes with the running and starting watt. Starting watt is higher than the running watts. 

You will get the exact figure on the level of the appliance. Or you could search for the model number of the particular brand on the internet. 

Now, you need to list down all your appliances and summarize the total watts of your appliances. Say for, your appliances consume 7000 watts altogether. You should count it at least 100 watts higher than the number when buying the generator. 

Understanding the Difference Between Watt and Volts and Amps

Watt is the SI unit of power. It is named after James Watt. Watt measures the rate of energy transfer. 

Volts mean pressure. That means how strongly the current passes through the circuit. So, the higher voltage means the greater flow of the electrical current. 

Ont he other hands, Ampere is the SI unit of current. It measures the rate of electron flow. It insects how much power an appliance needs. 

Also Read: How Many Amps Does A Generator Produce?

Understanding the starting and running watt 

Most electrical appliances come with different starting and running watts. The starting or surge watt is a bit higher than the running watt. When the appliances like the freezer, heater, or AC start completely, they need lower power to continue. 

In some cases, the difference between starting and running watt is large. Especially for the heater, AC, Dish Washer, Central AC, Electric Stove, etc. 

So, beware of the starting watt and running watt before buying a generator for your home. If you are planning to run all the large appliances during the power outage, it would be great to buy at least a 1000-watt higher generator than your needs. 

How Many Watts Do Common Appliances Use?

The rule of thumb for running electric appliances is that the total wattage consumed by all appliances in your house should not exceed half the maximum power output (watts) of your generator.

That means, if all of your appliances consume 5000 watts, then you should go for a 10 thousand watts generator. Yes, 10 thousand watt portable generators are available in the market. But for typical home use, 5000 to 7000 thousand watts is enough. If you need extra power, then go for the more powerful generator. 

Here is the list of common starting watt and running watts of mostly use appliances. Anyway, the watt can vary from brand to brand and power outage. It is only for getting an idea. 

Home AppliancesStarting WattRunning Watt
AC (10000 BTU)22001500
Oven (800 Watt)13001300
Sump Pump (.5 hp)21501050
Garage Opener 1420720
Television 150150
DVD Player350350
Bulb 6060
Laptop 250250
Cell Phone Charger2525
Ceiling Fan 1200800
Central AC (3 ton)75003000
Dryer 68005400
Electric Water Heater40004000
Washing Machine 22501150
Vacuum Cleaner 11001100
Blender 800400
Coffee maker 600600
Toaster Oven 12001200
Electric Grill 16501650
Dishwasher 1500700
Freezer 1600800
Slow Cooker 250250

How to select the right generator Size and Type? 

So, you have elementary knowledge about the generator now. Now, it is time to decide what kind of generator you should buy. 

If you need to run small sensitive appliances like laptops, TV, woodworking tools, and others, you should consider the Inverter generator. With an inverter generator, you can go camping without any tension on the supply of electricity. 

On the other hand, if you just want to backup the most important appliances in the power outage like the freezer, AC, Dishwasher, etc, then you could go for the portable generator without an inverter generator. 

Now, it’s time to consider which generator should I choose. 

Why should you choose the right generator for your home? 


Safety is the first concern for using a generator. Usually, the generator is safe to use. But ignorance is the key to accidents. Short circuits and damage to the home appliances are common for using the wrong size generator. So, you should strictly follow the recommendation for using a generator. Don’t overload the generator. 

Safeguard the Sensitive electronics 

Now, everybody uses a smartphone and sensitive electronics. So, if you run a regular generator without inverter features, no doubt your appliances will be damaged. 

Prevent the failure of loading power 

The generator can not provide the desired load. It is a very common complaint from the homeowners. Using the right size generator, you will not face such type of problem. 

Increase the lifespan of the generator 

Generators are expensive. You will not buy a generator every year. You can use a generator from decade to decade by taking the right care. When you have the proper knowledge you can use the generator year after year without any major issues. 


Can A Portable Generator Run A Whole House?

Yes, if your home is not too large you can run your whole house with a portable generator. Some of the renowned portable generator brands like Champion produce 12000-watt portable generators. So, if your power consumption is under this line, you could power your whole house with a portable generator. 

How Much Does A Whole House Generator Cost?

The average cost of a whole house generator is 5000 USD in the US. It may vary from area to area. Also, it depends on the size of your home and what types of appliances you want to run. However, the cost is limited from 5000 USD to 25000 USD. 

Will A 7500-Watt Generator Run My House?

Yes, you could run the appliances of your house with a 7500-watt portable generator. As I mentioned earlier, for getting the maximum performance you should not exceed the 3750 watts line. That means the summation of the output watt of your appliance should not exceed 3750 watts to get the maximum performance from a 7500-watt generator. 

Will A 9000-Watt Generator Run A House?

Yes, you could run your house with a 9000-watt generator. With a 9000-watt generator, you can run almost every home appliance including the Central Air, Sump pump, Dishwasher, AC, and all other small appliances of your home. 

What size generator to run a 1500-1800 sq ft house?

It depends on the demand of how much power you need. Some people run their major appliances on natural gas like furnaces, ovens, dryers, hot water heaters, and others. So, they just need to run their freezer, light, and AC with the electricity. Your demand may be different from theirs. However, a 2250 watts to 4000 watts generator should be enough to run your 1500 sq ft house. Although you may not run all the appliances at once. 

What size generator to run a 2000 sq ft house?

A 2000 squire ft house is enough space to use all types of necessary appliances like refrigerator, freezer, air conditioners, microwave oven, electric stove, LED bulb fans and etc. If you want to run all the home appliances you will need approximately 5000-8000 watt running watts. That means you need an 8000-watt to 10000-watt starting watt generator. 

On the other hand, if you just want to run only the basic appliances like refrigerator, lights, etc during the power wattage, 3000 watts to the 5000-watt generator is enough. 

what size generator do I need for a 2,500-square-foot house?

An atypical 2500 square foot house needs a 5000-8000 watt running watt. to run all your basic appliances including refrigerator, freezer, internet router, Directv box & TV, small drinks refrigerator, microwave oven, AC, and other small appliances. Just make sure that the starting watt of these household appliances doesn’t cross the power of your generator. So, the actual size depends on your needs. 

What size generator do I need for a 3000-square foot house?

3000 sp ft house with full packed appliances need a whole house generator to run all the appliances at once. But if you don’t want to run all your appliances during a power outage, you can backup your house with a large portable generator like a 12000-watt generator. Actually, it depends on your appliances. With a 12000 watt generator, you can run almost all the necessary home appliances like the sump pump, AC, heater, dishwasher, central air, furnace, and all the other home appliance. Yes, you can run all the appliances at a time but you can survive a prolonged power outage. 

Final Thoughts 

So, you could go for a powerful generator like a 10000 or 12000 starting watt portable generator to power up all your appliances. On the other hand, if you are looking for a solution including your sensitive electronics, then no doubt the inverter generators are the best solution. 


Rayan is an engineer, lives in a farmhouse. He has a passion for electronics and alternative energy. He loves to share his thoughts with other people. That is why he started the blog.

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