How to Convert Megajoules to Kilowatt-hours (MJ 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 megajoules into kilowatt-hours by hand, with examples and a quick-reference table.
The conversion
To convert megajoules to kilowatt-hours, multiply the value by 0.2777777778. To go the other way, divide by the same number (or multiply by 3.6). For a quick estimate, multiply by about 0.28.
Kilowatt-hours = megajoules × 0.2777777778
Worked examples
- 3 MJ = 0.833333 kWh
- 12.5 MJ = 3.4722 kWh
- 75 MJ = 20.8333 kWh
Megajoules to Kilowatt-hours table
| Megajoules | Kilowatt-hours |
|---|---|
| 1 MJ | 0.277778 kWh |
| 2 MJ | 0.555556 kWh |
| 5 MJ | 1.3889 kWh |
| 10 MJ | 2.7778 kWh |
| 20 MJ | 5.5556 kWh |
| 25 MJ | 6.9444 kWh |
| 50 MJ | 13.8889 kWh |
| 100 MJ | 27.7778 kWh |
| 250 MJ | 69.4444 kWh |
| 500 MJ | 138.8889 kWh |
| 1,000 MJ | 277.7778 kWh |
Common questions
Is MJ 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 Megajoules 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.
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.
Background
A conversion table is handy for common values, but a calculator is faster and avoids interpolation errors for anything in between.
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.
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 Megajoules to Kilowatt-hours Converter or browse all energy converters.
Run your own numbers: Megajoules to Kilowatt-hours Converter