How To Pick The Right Generator Size

Image by Sergey Isaev from Pixabay 

Choosing to buy a generator is risky whether we are talking about a household or business. 

However, since you can, on average, expect a large (4 or more hours) power outage once per year according to the U.S. Energy Information Administration, a generator may still be a worthwhile investment.

With this in mind, the most obvious question is—how big should your generator be? The answer is complicated, but the first thing on your mind when looking at different sizes is—buy the smallest generator that fits all of your needs and go 10 – 20% beyond.

How to Calculate Your Power Needs

A typical American household consumes 10,909 kilowatt-hours (kWh) per year or 909 kWh per month, but according to specific needs, you may want a generator that supports more or less than that. So, here’s a list of common household appliances and how much power they consume: 

  • Immersion heater 3000W
  • Electric fire 2000-3000W
  • Oil-filled radiator 500-2500W
  • Electric shower 7000-10,500W
  • Dishwasher 1050-1500W
  • Washing machine 1200-3000W
  • Tumble dryer 2000-3000W
  • Iron                                   1000-1800W
  • Vacuum cleaner 500-1200W
  • Plasma TV 280-450W

Some devices may use more or less power than listed here, so you may want to check them beforehand.

What to do When You’ve Calculated How Much You Require

When you’ve calculated the power usage you’ll need from your generator, you should start looking into different generators that fit your criteria. A general classification of different generator types goes like this:

Portable Generators

The best Portable Generators are exactly what their name says—portable! They vary a lot in size and capacity, are extremely versatile, and you can practically move them around as you please. Moreover, you can use them for everything—from charging your phone to an electric lawnmower. 

People often use them as camping trip accessories, and you can buy them either online or in most home improvement brick-and-mortar stores.

Power production: 100W–7,000W

Cost : $400–$3,000


This is the most common kind of generator and is perfect for securing the most important household appliances—such as a freezer or refrigerator—from losing power. The best Inverter generators work by throttling power, thereby reducing fuel usage so that it wastes less fuel when not at max capacity. They’re very affordable and available to buy online. When it comes to their quality, it ranges from recreational to professional.

Power production: 500W–7,500W

Cost : $400–$4,000

Whole House Generators

Best of the best, the whole house or household generator is designed to generate enough electricity to power the whole house, and anything else you might need. If you live in a place where the power isn’t reliable and need to be sure you’ll have power in case of blackouts, this is the choice for you. To install these machines, you will need to order them online, through specialised sellers, and have an expert with you for the job.

Power production: up to 20,000W

Cost : $2,000–$7,000