Authoritative definitions of the International System of Units and SI prefixes.
Dedicated unit pair
Watt-hours to Kilojoules
Convert Wh to kJ instantly, then review the formula, assumptions, and rounding guidance.
Energy, work, heat & powerInstant result
Decimals
Formula result = input × 3600 ÷ 1000. 1 Wh = 3.6 kJ
Common examples
One value, several units
Joules3,600 J
Kilojoules3.6 kJ
Megajoules0.0036 MJ
Kilowatt-hours0.001 kWh
Thermochemical calories860.4207 cal
Kilocalories0.8604 kcal
BTU (International Table)3.4121 BTU
Conversion table
| Wh | kJ |
|---|---|
| 1 Wh | 3.6 kJ |
| 2 Wh | 7.2 kJ |
| 5 Wh | 18 kJ |
| 10 Wh | 36 kJ |
| 25 Wh | 90 kJ |
| 50 Wh | 180 kJ |
| 100 Wh | 360 kJ |
Conversion chart
1 Wh3.6 kJ
5 Wh18 kJ
10 Wh36 kJ
25 Wh90 kJ
50 Wh180 kJ
Worked example
1 kilowatt-hour equals exactly 3.6 megajoules.
Unit definition
Watt-hours (Wh) One watt-hours equals 3,600 joule.
Unit history
Watt-hours is represented here using its modern SI definition or an internationally accepted relationship to an SI base unit.
Step by step
1. Parse the value, including fractions.
2. Convert Wh to joule.
3. Convert the base value to kJ and apply your display precision.
Understand the result before using it
Watt-hours to Kilojoules converts a value measured in Watt-hours (Wh) into the equivalent value in Kilojoules (kJ). The numerical value changes because the size and definition of the selected unit changes; the underlying quantity does not.
Calculated result
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.
Formula, assumptions, and example
Formula
result = input × 3600 ÷ 1000
Assumptions
- Watt-hours and Kilojoules represent the same energy, work & heat quantity.
- The input is expressed in Wh; the output is expressed in kJ.
- The unit definitions and conventional relationship shown on this page apply.
Worked example
1 Wh = 3.6 kJ. For another value, apply the same relationship and round only to the precision your source measurement supports.
When to use it
Good uses
- Read a Wh measurement in a document that expects kJ.
- Compare a watt-hours value with a value reported in kilojoules.
- Check the Wh-to-kJ arithmetic before copying the result into another calculation.
Limitations
Common mistakes to avoid
- Do not confuse Wh with another unit that has a similar name or symbol.
- Round the output to a precision justified by the original measurement.
- Verify safety-critical, regulated, laboratory, and contractual conversions against the controlling standard.
Sources and further reading
These references explain the underlying standards or provide authoritative context. Your own contract, institution, clinician, product documentation, local code, or governing standard may be the controlling source.
Guidance on unit names, symbols, conversions, and numerical presentation.
Questions about this calculation
How do I convert Watt-hours to Kilojoules?
result = input × 3600 ÷ 1000 Using the displayed relationship, 1 Wh equals 3.6 kJ.
How many Kilojoules are in one Watt-hours?
One Watt-hours is 3.6 Kilojoules. The displayed digits may be rounded.
Can I reverse the Wh to kJ conversion?
Yes. Swap the source and target units in the converter. The reverse relationship converts kJ back to Wh.
Is the Watt-hours to Kilojoules result exact?
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.