How to convert joules to kilowatt-hours
- Take the value in joules.
- Use the formula kilowatt-hours = joules × 2.777777778e-7.
- For example, 54,000 J is 0.015 kWh.
About joules and kilowatt-hours
A watt is one joule per second, and a kilowatt-hour is 1,000 watts for 3,600 seconds, so 1 kWh is exactly 3,600,000 J. Divide joules by 3.6 million to get kWh. With megajoules it is simpler: divide MJ by 3.6.
Physics problems, food labels and gas or fuel data often give energy in joules, kilojoules or megajoules, while electricity is billed in kWh. Converting puts both on one scale, so you can see what a battery, a meal or a tank of fuel is worth in electricity terms.
Examples
- 54,000 J (a 15 Wh phone battery) is 0.015 kWh
- 1,000,000 J (one megajoule) is 0.278 kWh
- 3,600,000 J (one kilowatt-hour) is 1 kWh
- 8,368,000 J (a 2,000 kcal day of food) is 2.32 kWh
Joules to kilowatt-hours chart
| Joules (J) | Kilowatt-hours (kWh) |
|---|---|
| 1 | 2.777778e-7 |
| 100 | 0.0000278 |
| 1,000 | 0.000278 |
| 3,600 | 0.001 |
| 10,000 | 0.00278 |
| 100,000 | 0.0278 |
| 360,000 | 0.1 |
| 500,000 | 0.139 |
| 1,000,000 | 0.278 |
| Joules (J) | Kilowatt-hours (kWh) |
|---|---|
| 2,000,000 | 0.556 |
| 3,600,000 | 1 |
| 5,000,000 | 1.39 |
| 10,000,000 | 2.78 |
| 36,000,000 | 10 |
| 50,000,000 | 13.89 |
| 100,000,000 | 27.78 |
| 1,000,000,000 | 277.78 |
| 3,600,000,000 | 1,000 |