Watt Hour Calculator
Convert a battery or device rating into watt-hours. Enter volts and amp-hours for a battery, or watts and hours for a device, and see the energy in watt-hours, kilowatt-hours and milliamp-hours.
How to calculate watt-hours
- Choose your inputs: volts and amp-hours, or watts and hours.
- Enter the two values from the battery or device label.
- Read the energy in watt-hours and kilowatt-hours.
- For a battery, also read the capacity in milliamp-hours.
Examples
12 V battery rated 100 Ah
12 volts, 100 amp-hours
1200 Wh, 1.2 kWh, 100000 mAh
Frequently asked questions
How do I turn amp-hours into watt-hours?
Multiply the voltage by the amp-hours. A 12 volt battery rated 100 Ah holds 12 times 100, which is 1200 watt-hours.
How do watts and hours give watt-hours?
Multiply the power in watts by the time in hours. A 60 watt device running 5 hours uses 60 times 5, which is 300 watt-hours.
What is the difference between mAh and Wh?
Milliamp-hours measure charge at a given voltage, while watt-hours measure energy. Watt-hours let you compare packs of different voltages fairly.
Why is there no mAh for watts and hours?
Milliamp-hours depend on voltage, which the watts and hours inputs do not include. So a charge figure only appears when you enter volts and amp-hours.
How do I convert watt-hours to kilowatt-hours?
Divide watt-hours by 1000. So 1200 watt-hours is 1.2 kilowatt-hours, the unit your power bill uses.
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