Calculator
Convert watt-hours to amp-hours
Convert energy in watt-hours to battery capacity in amp-hours at a given system voltage. Ah = Wh ÷ V.
Watt-hours measure energy independent of voltage; amp-hours are the rating printed on the battery itself, and depend on system voltage — the same 1,200Wh is 100Ah at 12V but only 25Ah at 48V. Convert to Ah at your actual system voltage before comparing against a battery's nameplate rating or sizing a bank.
Related calculators
Convert amp-hours to watt-hours
Battery bank size for your daily load
Usable capacity after depth-of-discharge
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
- IEEE 1013 — Recommended Practice for Sizing Lead-Acid Batteries for Stand-Alone Photovoltaic Systems — Widely used engineering practice for days-of-autonomy and depth-of-discharge sizing methods, referenced here for the general sizing approach.
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.