Convert joules to watt-hours
Enter a value in joules (J) to get watt-hours (Wh). One joule is 0.00027778 watt-hours; one watt-hour is 3,600 joules.
How to use the Joule to watt-hour
- Type the number of joules.
- Click Convert.
- Read the result in watt-hours, plus the same value in every other energy unit.
J to Wh formula
watt-hours = joules × 0.00027778. To go the other way, joules = watt-hours × 3,600 (see watt-hours to joules).
Worked example
12 J × 0.00027778 = 0.003333 Wh.
Joules to watt-hours conversion table
| Joules | Watt-hours |
|---|---|
| 0.1 J | 0.00002778 Wh |
| 0.5 J | 0.00013889 Wh |
| 1 J | 0.00027778 Wh |
| 2 J | 0.00055556 Wh |
| 3 J | 0.00083333 Wh |
| 5 J | 0.001389 Wh |
| 10 J | 0.002778 Wh |
| 20 J | 0.005556 Wh |
| 25 J | 0.006944 Wh |
| 50 J | 0.013889 Wh |
| 100 J | 0.027778 Wh |
| 250 J | 0.069444 Wh |
| 500 J | 0.138889 Wh |
| 1,000 J | 0.277778 Wh |
About the joule
The SI unit of energy: one newton-metre, or one watt for one second.
About the watt-hour
Battery capacity of phones and laptops.
Related conversions
Frequently asked questions
How many watt-hours in a joule?
0.00027778 watt-hours.
How many joules in a watt-hour?
3,600 joules.
Is the factor exact?
The factor 0.00027778 is derived from the units' exact definitions; only the display is rounded.
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Last updated 2026-09-23.