How to Convert Joules to Kilowatt-hours (J 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 joules into kilowatt-hours by hand, with examples and a quick-reference table.
The conversion
To convert joules to kilowatt-hours, multiply the value by 2.777778e-07. To go the other way, divide by the same number (or multiply by 3,600,000). Because the factor is tiny, scientific notation keeps the numbers manageable.
Kilowatt-hours = joules × 2.777778e-07
Worked examples
- 3 J = 8.333333e-7 kWh
- 12.5 J = 3.472222e-6 kWh
- 75 J = 2.083333e-5 kWh
Joules to Kilowatt-hours table
| Joules | Kilowatt-hours |
|---|---|
| 1 J | 2.777778e-7 kWh |
| 2 J | 5.555556e-7 kWh |
| 5 J | 1.388889e-6 kWh |
| 10 J | 2.777778e-6 kWh |
| 20 J | 5.555556e-6 kWh |
| 25 J | 6.944444e-6 kWh |
| 50 J | 1.388889e-5 kWh |
| 100 J | 2.777778e-5 kWh |
| 250 J | 6.944444e-5 kWh |
| 500 J | 0.000139 kWh |
| 1,000 J | 0.000278 kWh |
Common questions
Is J 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 Joules 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.
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
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.
Background
Unit conversion is simply multiplication by a fixed ratio. The ratio between two units of the same quantity never changes, so once you know it you can convert any value in either direction.
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
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 Joules to Kilowatt-hours Converter or browse all energy converters.
Run your own numbers: Joules to Kilowatt-hours Converter