What Size Generator Do I Need to Run My House?

With the increasing frequency of power outages and natural disasters that can cripple the electric grid, having a generator has become a vital piece of equipment for many homeowners. But, with so many different options available on the market, it can be difficult to determine the right size generator for your home

How Large A Generator You Need For A House

If you find yourself in this predicament, wondering “What size generator do I need to run my house?”, this article is here to help. We will go in-depth on the different factors to consider when choosing the right generator size, such as determining the recommended power consumption for your MIG welder, sump pump, and air compressor.

By the end of this article, you will be equipped with the knowledge you need to make an informed decision on the perfect generator size for your home. Don’t let confusion hold you back from being prepared for power outages, let’s find the right generator for you.

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

When it comes to measuring power, watts (W) is the universal unit that we use. The power range of a generator can vary significantly depending on the type of generator. For example, a camping generator typically has a power range of 1,000w to 3,000w, while a heavy-duty generator can have a power range that exceeds 10,000w.

It’s important to remember that a generator must be properly sized in relation to your energy requirements in order to effectively power a house. Choosing a generator that can output the right amount of power to keep your appliances and devices running is crucial.

This means that, if you have a large home with many appliances, you might need a generator with a power range of over 10,000w. On the other hand, if you have a small home with few appliances, a camping generator with a power range of 1,000w to 3,000w might be sufficient. By taking the time to assess your energy needs, you can ensure that you select the right generator size for your home.

1. Pick the Devices You Will Use

When considering purchasing a generator for your home, one of the most important steps is to make an inventory of all the appliances and devices that need to be powered in case of a power outage. This includes not only the obvious ones such as your air conditioner and refrigerator,

but also other essential items that you may not immediately think of such as lighting, security systems, and medical devices.

By creating a comprehensive list and determining the total power consumption of each item, you’ll be better equipped to choose the appropriate generator size that will meet your home’s needs during a power outage. This will ensure that your home stays comfortable and functional even when the power goes out.

2. Calculate Your Power Requirements

When searching for the right generator to power your home, it’s crucial to keep an eye on two key metrics:

  • Starting watts: This is the power required to start an appliance, and it’s often higher than the power required to keep the appliance running.
  • Running watts: This is the power required to keep an appliance running after it has been started.

It’s important to note that many appliances have different starting and running wattage requirements, and to determine the power consumption of your appliances you will need to consider both starting and running wattage.

Make sure to take this into account when selecting the generator size, to ensure that your generator can handle the power requirements of your home. By understanding the difference between starting and running wattage, you can confidently choose a generator that will keep your home running smoothly even during a power outage.

3. Opt For A Generator Slightly Larger Than You Need

When it comes to choosing the right generator for your home, there are a few key points to consider:

  • Power availability: It’s always better to have a generator with slightly higher power output than your current requirements, it gives you the flexibility to handle unexpected power surges.
  • Lifespan: Running a generator at less than full capacity can help prolong its lifespan, as it’s not being pushed to its limits.
  • Noise reduction: If you’re looking for a generator that runs quietly, you might consider getting one that is designed to run at half load, it can reduce the noise level.

When determining the power requirements for your home, it’s important to consider all your appliances, both running and starting. For instance, if your running appliances require 1600-1800 watts and your starting appliances require 6800 watts, a generator with at least 2000 rated watts should be sufficient.

Similarly, if your running appliances require 6800 watts and your starting appliances require 8200 watts, you should consider getting a generator with 9500 starting watts.

By keeping these factors in mind, you can ensure that you choose the perfect generator for your home that will meet your power needs and keep your home running smoothly during power outages.

Electric Appliances And Their Wattage Consumption

Uncover the precise wattage by crafting this simple list, even if you’re facing challenges.

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

A 24,100W generator is the ideal starting point, but if you’re looking to power only life’s 

necessities, opt for 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

When faced with this situation, a 35kW generator for your entire home is probably a necessity.

Watts versus Amps versus Volts

Calculating the energy consumption or production of electrical equipment requires a combination of watts (W) and amps (A). While the standard voltage (V) in the U.S. for household appliances is 120V, certain high-voltage tools like TIG and MIG welders break the mold.

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

A generator’s crucial role is to maintain stable voltage and frequency. AC electricity is a staple, but generators also supply DC power.

A dual-power approach, AC and DC, provides versatility for electronics to operate efficiently at lower voltages and still grants considerable power at reasonable costs. Homes with solar panels or wind turbines can maximize energy efficiency by incorporating batteries to store surplus electricity during lulls in sunlight or wind.

Availability of Fuel

Fuel type influences a generator’s functioning. Backup generators running on natural gas, propane, or diesel may be preferred, so long as fuel supply is constant.

While less environmentally sound, these fuels generate higher energy output, ideal for powering appliances with elevated energy demands like air conditioners during scorching summer heatwaves.

Multi-fuel capable models may be ideal for homes relying on a mix of energy sources like solar panels and oil tanks that may change frequently.

Capacity (Size/Weight)


For powering a few crucial circuits in a typical home, generators of this size are a fit. Homes with two levels or fewer, and equipped with manual switches for targeted usage, benefit most from these generators.

For those in need of a compact yet mighty generator, I recommend Honda’s 150-pound model, the largest small generator I endorse.


For homes of medium size or moderate but consistent energy demands, medium-sized generators offer a solution.

Eliminating human error, these systems come equipped with automatic transfer switches for seamless integration into your electrical system – just a few circuits are needed for the average home.

Typically powered by a gas engine, a medium generator generates a steady flow of 6000 to 8000 watts.


For homes with significant power needs, large generators offer a comprehensive solution. Unlike medium generators, these systems can power multiple circuits at once, making it possible to connect every room of your multi-story home with automatic and manual transfer switches.

Ranging from 12000 to 180000 watts, these generators are equipped to handle any energy requirements, except in cases where the property has excessive energy needs.

With their capacity for high output and versatility, large generators are ideal for larger homes with substantial power demands.


For a three-bedroom house, what size generator is needed?

For a 3-bedroom residence, a power supply in the range of 3000-6000 watts is considered optimal.

Can a 20kw generator power my house?

With a 20kW generator, powering your household lights, AC, and outlets is feasible. However, if you’re relying solely on generator power, a separate heating/cooling setup for the upper level is not required.

Are 12000-watt generators sufficient to run a house?

A 12,000-watt generator can supply uninterrupted power to your home, powering all essential appliances including lights, fans, televisions, refrigerators, computers, and space heaters.

In order to power a 1,500 square foot home, what size generator do I need?

For a home measuring 1500 square feet, a generator with a power output between 2200 and 4000 watts would suffice. If your plan is to only run limited appliances and not the air conditioner, a generator generating 2200 watts should be enough.

Is a generator capable of powering a whole house?

Generators come in different sizes to accommodate various power needs. A compact generator can support a few appliances, while a larger backup generator can provide electricity to the entire home. Choosing the right size depends on your intended usage.


Choosing the right generator for your home requires careful consideration of various factors, with the output power (kW) being the most critical. Besides that, the reliability and versatility of the generator are equally important.

A Honda 7000-watt generator is a great option for ensuring your essential appliances keep running in case of an emergency. It features a voltage regulator to avoid overloading and issues from grid fluctuations caused by storms.

If you found this guide on “What size generator do I need for my house?” useful, don’t hesitate to share it with those in need, and let us know your thoughts by leaving a comment below.

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