HowWatt helps estimate battery runtime, required battery capacity and household device power use. Our goal is to make energy calculations accessible and explain what each result means.
Who builds HowWatt
Founder and developer: Vlad Fedorin, a designer and web developer from Ukraine. The project grew from the practical need to understand backup power during electricity outages.
We publish formulas, examples and assumptions. The calculators do not replace professional electrical system design or establish compatibility of specific equipment.
Calculation independence
This version has no advertisements or affiliate links. Future advertisements and affiliate offers will be labelled.
Methodology updated October 6, 2026