Daily watt-hours for a device
Calculate the daily energy a device uses in watt-hours from its power draw, run time and quantity.
Daily watt-hours is the real measure of how much energy a device actually uses, not just its power rating — a 100W device running 8 hours a day uses the same 800Wh as a 400W device running 2 hours. Add up every device's daily Wh to get the total daily load a battery bank and solar array need to be sized against.
Related calculators
Looking for a definition or a quick answer? See the solar & battery glossary for terms used on this page, or the FAQ for common sizing questions.
Sources & standards
- ENERGY STAR Product Finder — US EPA/DOE database of tested annual/typical energy use for major household appliances.
- U.S. EIA — Electricity Use in Homes — Federal reference on typical household electricity consumption by end use.
Estimates for planning only. Verify with a meter and follow NEC / local code; have a licensed installer confirm any system before purchase or wiring. See the methodology for formulas and sources.