Generator Sizing Calculator

Wondering what size of portable generator you need? Our generator sizing calculator will help you determine your electrical power needs and suggest the right portable generators for you.

Each portable generator has two main specs, running watts and starting watts. You can learn more about them in an article dedicated to this topic. The wattage calculator below eliminates the need to refer to a wattage chart. It will estimate the total wattage you need to power all your appliances.

How Does it Work?

You’ll first need to choose what the main use of your generator will be.

  • Choose Recreational if you wish to find a generator for your RV, your DIY activities, your camping trips, tailgating or for your outdoor events
  • Choose Home if you wish to find a generator to use as backup power or primary power for your home
  • Choose Pro if you wish to find a generator suitable for powering tools, for construction work or for farm work

You’ll then be able to choose appliances that relate to this use and/or to add your own custom appliances. You may also select names of your preferred manufacturers.

Select your principal use

Show all appliances

Select all the appliances you wish to simultaneously power

Would you prefer any specific brand(s)?

Do you intend to use your generator at high altitudes?

At what altitude? feet

A generator can lose around 3% of its power for every 1000 ft. Learn more > (opens in a new tab)

Add your own appliances or tools

Item Running watts Additionnal
starting watts
Your custom item\'s running watts must first be filled in, before adding a new item.
Generator Bible
Compare items
  • Total (0)

You can compare as many generators as you wish. However, for the best results, we recommend you to compare only 2 generators at a time.