How to Convert Kilojoules to Kilowatt-hours (kJ to kWh)
Energy conversions link food labels in kJ and kcal, SP Group bills in kWh and air-conditioner capacity in BTU. This guide shows how to convert kilojoules into kilowatt-hours by hand, with examples and a quick-reference table.
The conversion
To convert kilojoules to kilowatt-hours, multiply the value by 0.0002777778. To go the other way, divide by the same number (or multiply by 3,600). Because the factor is tiny, scientific notation keeps the numbers manageable.
Kilowatt-hours = kilojoules × 0.0002777778
Worked examples
- 3 kJ = 0.000833 kWh
- 12.5 kJ = 0.003472 kWh
- 75 kJ = 0.020833 kWh
Kilojoules to Kilowatt-hours table
| Kilojoules | Kilowatt-hours |
|---|---|
| 1 kJ | 0.000278 kWh |
| 2 kJ | 0.000556 kWh |
| 5 kJ | 0.001389 kWh |
| 10 kJ | 0.002778 kWh |
| 20 kJ | 0.005556 kWh |
| 25 kJ | 0.006944 kWh |
| 50 kJ | 0.013889 kWh |
| 100 kJ | 0.027778 kWh |
| 250 kJ | 0.069444 kWh |
| 500 kJ | 0.138889 kWh |
| 1,000 kJ | 0.277778 kWh |
Common questions
Is kJ to kWh exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Kilowatt-hours to Kilojoules converter.
Mistakes to avoid
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Background
Singapore adopted the metric system in the 1970s, replacing imperial units and traditional Chinese measures in most official uses. Metric units are now standard in schools, trade and government, but older units survive in property, markets and imported goods.
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
For any value, use the Kilojoules to Kilowatt-hours Converter or browse all energy converters.
Run your own numbers: Kilojoules to Kilowatt-hours Converter