Watt-hours = watts × hours
Formula: Wh = W × h
If you know volts and amps: Wh = V × A × h
If you know amp-hours and volts: Wh = V × Ah
Example: 100 W × 2 h = 200 Wh
Example: 12 V × 10 Ah = 120 Wh
To convert from watt-hours to kilowatt-hours: kWh = Wh ÷ 1000
To convert from kilowatt-hours to watt-hours: Wh = kWh × 1000