How to Convert Kilowatt-hours to Joules (kWh to J)
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 joules by hand, with examples and a quick-reference table.
The conversion
To convert kilowatt-hours to joules, multiply the value by 3,600,000. To go the other way, divide by the same number (or multiply by 2.777778e-07). For a quick estimate, multiply by about 3,600,000.
Joules = kilowatt-hours × 3,600,000
Worked examples
- 3 kWh = 10,800,000 J
- 12.5 kWh = 45,000,000 J
- 75 kWh = 270,000,000 J
Kilowatt-hours to Joules table
| Kilowatt-hours | Joules |
|---|---|
| 1 kWh | 3,600,000 J |
| 2 kWh | 7,200,000 J |
| 5 kWh | 18,000,000 J |
| 10 kWh | 36,000,000 J |
| 20 kWh | 72,000,000 J |
| 25 kWh | 90,000,000 J |
| 50 kWh | 180,000,000 J |
| 100 kWh | 360,000,000 J |
| 250 kWh | 900,000,000 J |
| 500 kWh | 1,800,000,000 J |
| 1,000 kWh | 3,600,000,000 J |
Common questions
Is kWh to J 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 Joules to Kilowatt-hours converter.
Mistakes to avoid
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
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.
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.
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 Joules Converter or browse all energy converters.
Run your own numbers: Kilowatt-hours to Joules Converter