How Big Does a Whole House Generator Need to Be?

how big does a whole house generator need to be

Buying a whole house generator can be a daunting task. There are many factors to consider, including size, price, and maintenance. Here are some of the basics to keep in mind as you decide what’s best for your home.

Start-up wattage

The start-up wattage of a whole house generator is important to know before purchasing one. Depending on the size of your house, you may need a large generator. When choosing a generator, you should consider the wattage of your appliances and how long your home will be without power.

Some appliances have different wattages, such as air conditioners and refrigerators. In addition, some of your appliances will require extra power when they are turned on. For example, a freezer will run at 1,000 watts at its peak and at 400 watts during its run-down.

To figure out the wattage of your appliances, you can use a wattage reference chart, or you can take a wattage meter to the nearest local expert. While nameplate data is more accurate, a wattage meter is the best option in most cases.

Running wattage

When planning to use a whole house generator, it’s important to know the running wattage of all appliances in your home. This will help you calculate your total wattage needs. The wattage or power requirement of the appliances is usually listed on the appliance manual.

It’s also important to keep in mind that some appliances have separate starting and running wattages. Appliances such as refrigerators, coffee makers, and hot plates draw more wattage when turned on. However, other appliances such as light bulbs do not require extra wattage boosts when turned on.

You can use a generator calculator or generator sizing sheet to figure out the total wattage you need. Depending on your needs, you may want to consider a smaller generator to power only a few appliances. Or, you might opt for a larger one to cover your entire house in case of an emergency.

Surge wattage

Surge wattage is the extra surge power you need to start your electric motors. This is also known as starting watts, and you can determine how much you need to run your generator by looking at the labels on your appliances.

The amount of energy your generator needs is dependent on how many devices you have. In general, a small generator can power two to three appliances. Having more than that means you could experience power overload and risk breaking your generator. You can estimate how much power you will need using a wattage requirement calculator.

Buying a whole house generator means that you will be able to power your entire home. However, you need to account for the surge wattage of your large appliances. These are appliances that produce heat when they are on. For example, you may need to turn on your air conditioner to warm up your home.

Proper maintenance

You should always have a professional check your whole house generator once or twice a year to ensure it continues to function as it should. Not only can this prevent premature failure, but it will also extend the lifespan of your backup generator.

A professional can also tell you when your battery is nearing its end of life. When your battery is in the final stages of life, it’s time to replace it.

Before you have a technician do any maintenance work on your whole house generator, make sure to disconnect all power supplies. Also, be sure to clean the area around the unit. Debris can build up and block the vents, which can cause dangerous gas leaks and other problems.

During the maintenance process, you should also check for loose wires, damaged guards, and corrosion. An air filter is important to keep dirt from clogging the engine.


A whole house generator is a standby power system that is designed to keep your entire home up and running in the event of a power failure. It can also help increase your home’s resale value.

Whole house generators come in a variety of sizes and costs. They range from several hundred to several thousand dollars, depending on the model and size you choose.

Most of these devices are designed to work with your existing electrical systems and will automatically engage when your power goes out. They can alert you through error messages or through changes in your home’s standby lights.

Whether you opt for a portable or a fixed-size generator, you’ll need to purchase the fuel you’ll need to run your new device. Diesel or natural gas are both good choices. Liquid propane is another option. These are usually less expensive than gasoline generators.