About Generator Watt Calculator
Generator Watt Calculator is a free, brand-neutral site that helps homeowners and RV owners work out what size generator they need, how long it will run, and how to use it safely.
Why we built it
Most generator sizing tools online are made by generator brands, and they end on a product page. That is fine if you already like the brand, but it makes it hard to see the math. We wanted a calculator that shows every step, uses published ranges rather than a single flattering number, and tells you when a smaller unit plus some load management would do.
Outages are getting longer for many households. The U.S. Energy Information Administration reported that the average electricity customer went about 11 hours without power in 2024, the most in a decade, largely because of hurricanes. When people shop for a generator, it is often in a hurry, right before or after a storm. Clear numbers help.
What you will find here
A generator size calculator with running and starting watts for common household loads, an RV amp calculator for 30-amp and 50-amp hookups, a fuel run-time estimator that uses your generator’s own spec sheet, a watts-amps-volts converter, and an outage prep checklist. The guides explain transfer switches, carbon monoxide safety, fuel storage, and how to read a generator spec sheet.
Who writes it
Generator Watt Calculator is written and maintained by a small editorial team at an independent web publisher. We are not lawyers, engineers, doctors, or government officials, and we do not claim to be. What we do is read the primary sources (statutes, agency guidance, university extension publications, and official court and health-department pages), turn them into plain steps, and link every claim back to where it came from.
How the site is paid for
The site is free to use and is supported by display advertising from Google. Advertisers do not choose or review our topics, and ads never change what a guide says. Read our editorial standards for how we pick sources, correct mistakes, and keep ads separate from content.
Tell us what we got wrong
Rules change and local details vary. If you spot an error or an out-of-date figure, please send us a note with a link to the source. We read every correction and date-stamp the fix.
Photo and video credits
Home page background video (storm clouds over a transmission tower) by Bhumik Photography on Pexels, used under the Pexels license.