Understanding Battery Watt-Hours (Wh)
What watt-hours mean, how to convert from Ah, and why Wh matters for solar and EV planning.
Watt-hours (Wh) measure energy—the total amount of work a battery can deliver. Unlike amp-hours (Ah), Wh accounts for voltage, which makes it the best unit for comparing packs of different chemistries and voltages.
The simple formula
For any battery: Wh = Ah × V. A 100 Ah 12 V lead-acid battery stores 1,200 Wh. A 50 Ah 48 V lithium pack stores 2,400 Wh—twice the energy despite half the amp-hours.
Use WattQuick's Ah to Wh and Wh to Ah converters for instant conversions while planning a system.
Why it matters for solar and EV
Solar loads and appliance labels are usually in watts or kilowatt-hours. EV chargers and utility bills use kWh. Converting your battery to Wh lets you answer: how many hours will this run, or how much of my pack does this trip use?