How to Convert Kilowatt-hours to Kilojoules (kWh to kJ)
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 kilowatt-hours into kilojoules by hand, with examples and a quick-reference table.
The conversion
To convert kilowatt-hours to kilojoules, multiply the value by 3,600. To go the other way, divide by the same number (or multiply by 0.0002777778). For a quick estimate, multiply by about 3,600.
Kilojoules = kilowatt-hours × 3,600
Worked examples
- 3 kWh = 10,800 kJ
- 12.5 kWh = 45,000 kJ
- 75 kWh = 270,000 kJ
Kilowatt-hours to Kilojoules table
| Kilowatt-hours | Kilojoules |
|---|---|
| 1 kWh | 3,600 kJ |
| 2 kWh | 7,200 kJ |
| 5 kWh | 18,000 kJ |
| 10 kWh | 36,000 kJ |
| 20 kWh | 72,000 kJ |
| 25 kWh | 90,000 kJ |
| 50 kWh | 180,000 kJ |
| 100 kWh | 360,000 kJ |
| 250 kWh | 900,000 kJ |
| 500 kWh | 1,800,000 kJ |
| 1,000 kWh | 3,600,000 kJ |
Common questions
Is kWh to kJ 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 Kilojoules to Kilowatt-hours converter.
Mistakes to avoid
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Forgetting squared and cubed units
Area and volume factors are the length factor squared or cubed, so 1 m² is about 10.76 sq ft, not 3.28.
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Background
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.
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.
For any value, use the Kilowatt-hours to Kilojoules Converter or browse all energy converters.
Run your own numbers: Kilowatt-hours to Kilojoules Converter