How many kilojoules are in a watt-hour?

One watt-hour equals exactly 3.6 kilojoules. This is because 1 Wh = 3600 joules = 3.6 kJ. The conversion factor is always 3.6.

What is the formula to convert Wh to kJ?

kJ = Wh × 3.6. For example, 10 Wh = 10 × 3.6 = 36 kJ. To reverse: Wh = kJ ÷ 3.6.

A watt is one joule per second, so 1 Wh = 1 W × 3600 s = 3600 J = 3.6 kJ. Multiplying by 3.6 converts from Wh to kJ.

Can I convert kilojoules back to watt-hours?

Yes. Switch to reverse mode and enter kilojoules. The tool divides by 3.6 to give watt-hours.

Is a watt-hour the same as a kilowatt-hour?

No. A kilowatt-hour (kWh) equals 1000 Wh or 3600 kJ. Watt-hours (Wh) are much smaller: 1 Wh = 3.6 kJ, while 1 kWh = 3600 kJ.

Where is Wh to kJ conversion used in practice?

Common in battery spec sheets, electrical engineering, food science (comparing food energy in kJ with electrical storage in Wh), and physics coursework.

Watt Hours to Kilojoules Converter

Enter a value in watt-hours to get the equivalent in kilojoules instantly, or switch to convert kJ back to Wh.

Convert Energy Units

Watt-Hours (Wh)

Result in Kilojoules (kJ)

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Batch Converter

Enter one value per line. Converts using the current direction.

Quick Reference

Wh	kJ

Summary

Enter a value in watt-hours to get the equivalent in kilojoules instantly, or switch to convert kJ back to Wh.

How it works

Enter a value in watt-hours (Wh) in the input field.
The converter multiplies by 3.6 to get kilojoules (1 Wh = 3.6 kJ).
The result in kilojoules appears instantly below the input.
Switch to reverse mode to convert kilojoules back to watt-hours.
Use the batch converter to process multiple values at once.
Check the quick reference table for common Wh to kJ conversions.

Use cases

Convert battery capacity from watt-hours to kilojoules for engineering specs.
Compare electrical energy storage (Wh) with thermal energy values (kJ).
Verify physics homework involving energy unit conversions.
Translate appliance energy ratings between Wh and kJ for international specs.
Calculate energy budgets for solar and battery storage systems.
Convert electrical energy figures for scientific reports or publications.

Frequently Asked Questions

Last updated: 2026-06-19 · Reviewed by Nham Vu