Joules to Watt-hours (J to Wh) Converter
1 joule equals 0.00027778 watt-hours — multiply joules by 0.00027778, or divide by 3,600, to convert J to Wh. A watt-hour is the energy of one watt sustained for one hour, which is exactly 3,600 joules.
The formula
To convert joules to watt-hours, multiply by the exact factor:
Wh = J × 0.00027778
For example, 3,600 J × 0.00027778 = 1 Wh. The factor is simply 1 ÷ 3,600.
Conversion table
| Joules (J) | Watt-hours (Wh) |
|---|---|
| 1 | 0.00027778 |
| 2 | 0.00055556 |
| 5 | 0.0013889 |
| 10 | 0.0027778 |
| 25 | 0.0069444 |
| 50 | 0.013889 |
| 100 | 0.027778 |
| 500 | 0.13889 |
| 1000 | 0.27778 |
| 3600 | 1 |
How to convert online
- Type the number of joules into the first box.
- Read the watt-hour result instantly in the second box.
- Or enter a Wh value to convert back to joules — it works both ways.
Use the Joule to Watt-hour Converter — free and instant in your browser.
Where this conversion is used
Watt-hours are the everyday way to describe battery and power-pack capacity — phone chargers, laptops and e-bike batteries are all rated in Wh — while joules are the scientific unit. Converting between them helps when you compare a device's energy store against a physics calculation, size a portable battery, or read a spec sheet that mixes the two units.
FAQ
How many watt-hours are in a joule?
One joule equals 0.00027778 Wh, which is one 3,600th of a watt-hour.
How many joules are in 1 Wh?
Exactly 3,600 joules make up one watt-hour.
How do I convert watt-hours back to joules?
Multiply the watt-hour value by 3,600. For example, 5 Wh = 18,000 J.
Is the conversion exact?
Yes. 0.00027778 is a rounded display of the exact fraction 1/3,600, and the tool keeps full precision internally.
Related converters
- Watt-hour to Joule Converter
- Joule to Kilojoule Converter
- Joule to Kilowatt-hour Converter
- Joule to Calorie Converter
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