Joules to watt-hours
Type a value in joules to see it in watt-hours straight away, or type in the second box to convert back.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Type the value in the joules box.
- Read the result in watt-hours as you type, and pick the precision you need.
- Swap the direction to convert back, or copy the result.
How it is calculated
Wh = J × 0.0002777777778
Multiply the value in joules by 0.0002777777778 to get watt-hours.
Example
To convert 25 J to watt-hours: 25 × 0.0002777777778 = 0.00694444 Wh.
Conversion table
| Joules (J) | Watt-hours (Wh) |
|---|---|
| 1 | 0.000277778 |
| 2 | 0.000555556 |
| 3 | 0.000833333 |
| 5 | 0.00138889 |
| 10 | 0.00277778 |
| 20 | 0.00555556 |
| 25 | 0.00694444 |
| 50 | 0.0138889 |
| 100 | 0.0277778 |
| 250 | 0.0694444 |
| 500 | 0.138889 |
| 1,000 | 0.277778 |
About the units
- Joule
- The SI unit of energy, equal to the work done by a force of one newton moving an object one meter.
- Watt-hour
- The energy used by a one watt device in one hour, exactly 3600 joules. Common for battery and power bank capacity.
Limits and caveats
- Results are rounded for display and computed with the browser's floating point precision (about 15 significant digits).
- Both unit factors are exact by their official definitions.
Questions about this tool
How many watt-hours are in one joule?
1 J = 0.000277778 Wh exactly.
How do I convert joules to watt-hours?
Use Wh = J × 0.0002777777778. For example, 25 J = 0.00694444 Wh.
How many joules are in one watt-hour?
1 Wh = 3,600 J.
Which calorie do these converters use?
The thermochemical calorie, exactly 4.184 joules, the factor many countries use to turn kcal into kJ on food labels. The International Table calorie is 4.1868 joules, less than 0.07% larger.
What is the difference between kW and kWh?
A kilowatt is a unit of power, the rate of using energy, while a kilowatt-hour is an amount of energy. A 2 kW heater running for three hours uses 6 kWh.