What Size Generator Do I Need to Run My House?

Share on:

Since people are experiencing power outages and natural disasters that break the electric grid, generators are becoming essential items for them.

For those who find themselves in situations like these, and have a generator, but aren’t sure what size generator do I need to run my house? This article is for you.

How Large A Generator You Need For A House

In spite of the fact that there are many generators available in the market, people are left confused, which one is best for their home? What is the recommended power consumption for my MIG welder/sump pump/air compressor?

In this article, we will explore this topic in great detail. As you read this article, you will certainly find the answers to your questions, such as what size generator is best for my house?

How To Calculate: How Large A Generator You Need For A House?

Watts (W) are the units we use to measure power. A small camping generator typically has a power range of 1,000w to 3,000w, while a heavy-duty generator can have a power range exceeding 10,000w.

A generator must be sized according to your energy requirements in order to power a house.

1. Pick the Devices You Will Use

If you need a generator for your home, make a list of every appliance you need to be able to use if the power goes out, such as your air conditioner, refrigerator, and lighting.

2. Calculate Your Power Requirements

Keep an eye out for:

  • Starting watts (wattage required to start the appliance)
  • Running watts(energy used by the appliance after it has been started)

3. Opt For A Generator Slightly Larger Than You Need

Due to these reasons:

  • There is extra power available of a few hundred watts
  • The lifespan is not significantly reduced (since it is not used fully)
  • Run at half load to reduce noise

Get a generator with at least 2000 rated watts if your current power requirements are 1600-1800 running watts, and if your running appliances are 6800 watts and your starting appliances are 8200 watts, choose a generator with 9500 starting watts.

Electric Appliances And Their Wattage Consumption

Here’s how you can create a list to find the exact wattage if you are having trouble making one.

Essentials Appliances

AppliancesStarting and Running Wattage
Washing Machine1,200/1,200
Refrigerator or Freezer2,900/7,00
Clothes Dryer6,750/5,400
2 Ton Central Ac8,750/3,800
Electric Water Heater4,500/4,500
Sum of Wattage24,100/15,600

The recommended starting wattage for a generator is 24,100W, so if you are only looking for a generator to run vital appliances, you would need a minimum 25kW generator.

Powering the Entire House

AppliancesStarting and Running Wattage
Garage door opener1,420/7,20
Security system550/550
Washing machine1,200/1,200
Clothes Dryer6,570/5,400
Refrigerator or Freezer2,900/700
2 Ton Central Ac8,750/3,800
Electric water heater4,500/4,500
Microwave oven1,300/1,300
Electric range2,100/2,100
2 TV (46”)380/380
8+ light fixtures1,100/1,100
Sum of Wattage31,560/22,216

You would probably need at least a 35kW whole-home generator in this situation.

Watts versus Amps versus Volts

In order to calculate the total power consumed or produced by electrical equipment, watts (W) and amps (Amps) are used. The most common volt (V) rating for electric appliances sold in the U.S. is 120V. Some electrical tools, such as TIG welders and MIG welders, operate at a higher voltage.

The following formula can be used to determine how much current your appliance or tool needs:

Wattage= Amps x 120

Example: A 120V MIG welding machine with a 70 Amp draw.

70A x 120V = 8400W

The welder needs at least 8,400 watts of power in this situation.

However, if you want to calculate your portable appliance’s amperage using your wattage, you can use the following formula:

Amps = Wattage / Voltage

What Are The Features I Should Look For In A Whole House Generator?

Providing a Stable Source of Power

Generators must produce constant voltages and frequencies. One of the most common types of electricity that generators provide is alternating current (AC), but they also deliver direct current (DC).

A combination of both AC and DC power is versatile because it allows sensitive electronics to operate at lower voltages, while DC offers greater potential at similar prices. For houses powered by solar panels or wind turbines, installing batteries can be helpful in storing surplus electricity during periods of insufficient sunlight or wind.

Availability of Fuel

A generator’s fuel type affects how it operates. You will want a backup generator that can run on natural gas, propane tanks, or diesel, as long as they have an uninterrupted supply of fuel.

Although it is less environmentally friendly, it also produces a higher amount of energy that can power more energy-hungry appliances, like air conditioning units during summer months when demand spikes due to heatwaves.

Some models can run on multiple fuel sources, so they may be a good option if your home runs off different sources such as solar panels and oil tanks at varying times.

Capacity (Size/Weight)


Generators of this size are generally used to power a few key circuits throughout an average residence. Furthermore, they are best suited to homes with no more than two levels, and many are equipped with manual switches that limit their use to certain areas. 

I recommend a Honda 150-pound generator as the largest small generator I recommend.


Medium-sized generators are generally used for medium-sized homes, or when power needs are pretty constant but not as huge as they would be for a large generator.

Automatic transfer switches come with these systems, which eliminate human error, making it relatively easy to hook up your own electrical system. You only need a few circuits for a typical home.

An average medium generator usually generates between 6000 and 8000 watts at any given moment and is generally powered by a gas engine 


Unlike medium-sized generators, large generators are able to power more than one circuit at a time. You can connect the entire house regardless of how many stories it has using automatic and manual transfer switches.

Depending on their size, these systems range from 12000 to 180000 watts, meaning they can power whatever you throw at them as long as you don’t have a lot of energy needs on your property. 

These types of generators are typically used by larger homes because of their high output and versatility.



A number of factors must be taken into account when choosing the correct size generator for your home (mentioned above). A unit’s output power (kW) is the most important consideration, but there are other factors to consider as well. 

A 7000-watt Honda generator is a good choice for your home. In case of an emergency, you can keep your essential appliances running. In addition, a voltage regulator built into the model prevents overloading and problems from occurring due to fluctuations in the grid caused by storms.

If you found this article informative about What size generator do I need to run my house? Then share it with your friends, family, and especially those experiencing similar problems. Also, feel free to share your thoughts with us by commenting down below.

MyGeneratorLab was founded and is headed by Kaif Rai. As a long-time outdoorsman, I've always been fascinated by generators. I founded MyGeneratorLab to share my knowledge of the best generators on the market with others. I provide reviews on generators with in-depth guides. I will help you learn how to maintain generators properly so they will last longer by using my guides! I started my generator reviews in 2021. Since then, I’ve had the privilege of experiencing and testing generators of all shapes and sizes.

Leave a Comment