Watt-hour (Wh)
Energy of one watt sustained for one hour: exactly 3600 joules.
What is a watt-hour?
- Symbol
- Wh
- Quantity
- Energy
- Unit system
- SI-accepted
- Definition
- Energy of one watt sustained for one hour: exactly 3600 joules.
- Exact
- Yes, the value is exact by definition
- Source
- SI Brochure, 9th edition (BIPM, 2019)
Common applications
Used for battery capacity in phones, laptops and power banks.
Watt-hour in other energy units
- 1 Wh = 3600 JJoule
- 1 Wh = 3.6 kJKilojoule
- 1 Wh = 0.0036 MJMegajoule
- 1 Wh = 0.001 kWhKilowatt-hour
- 1 Wh ≈ 860.4206501 calCalorie (thermochemical)
- 1 Wh ≈ 0.8604206501 kcalKilocalorie (thermochemical)
- 1 Wh ≈ 3.412141633 BTUBritish thermal unit (IT)
- 1 Wh ≈ 2655.223737 ft·lbfFoot-pound-force
- 1 Wh ≈ 2.246943267e+22 eVElectronvolt
- 1 Wh = 36000000000 ergErg
Watt-hour quick reference
| Watt-hour | Kilojoule | Kilocalorie (thermochemical) | Joule |
|---|---|---|---|
| 1 Wh | = 3.6 kJ | ≈ 0.8604206501 kcal | = 3600 J |
| 10 Wh | = 36 kJ | ≈ 8.604206501 kcal | = 36000 J |
| 100 Wh | = 360 kJ | ≈ 86.04206501 kcal | = 360000 J |
| 1000 Wh | = 3600 kJ | ≈ 860.4206501 kcal | = 3600000 J |
Where the watt-hour fits
The next smaller energy unit is the British thermal unit (BTU). 1 Wh ≈ 3.412141633 BTU, and 1 BTU ≈ 0.2930710702 Wh.
The next larger energy unit is the kilocalorie (kcal). 1 Wh ≈ 0.8604206501 kcal, and 1 kcal ≈ 1.162222222 Wh.
Frequently asked questions
- How many kilojoules are in one watt-hour?
- One watt-hour = 3.6 kJ (kilojoules).
- How many kilocalories are in one watt-hour?
- One watt-hour ≈ 0.8604206501 kcal (kilocalories).
- How many joules are in one watt-hour?
- One watt-hour = 3600 J (joules).