wh to kj | Exact Decimal + Formula

1 Watt-hour = 3.6 Kilojoule

One watt-hour equals about 3.6 kilojoules (exactly 3.6 kJ). Real-world use: battery capacities and small appliance energy consumption. This page expresses those values in kilojoules, which is used for food-energy labels in many countries and technical energy measurements. Enter any value above — the result updates instantly, and a 1–1000 reference table follows below.

About Watt-hour and Kilojoule

Watt-hour (Wh)

A watt-hour is one watt of power sustained for one hour, equal to 3,600 joules.

Where it's used: Battery capacities and small appliance energy consumption.

Kilojoule (kJ)

A kilojoule is 1,000 joules.

Where it's used: Food-energy labels in many countries and technical energy measurements.

Energy Converter

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Precision

Formula

kJ = Wh × 3.6

To convert Watt-hour to Kilojoule, use the formula displayed above.

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Watt-hour to Kilojoule: Quick Reference Table

Watt-hour	Kilojoule (Decimal)	Fraction	Real-world equivalent
0.001 Wh	0.0036 kJ	-	fractional unit measurement
0.01 Wh	0.036 kJ	-	fractional unit measurement
0.1 Wh	0.36 kJ	-	fractional unit measurement
0.5 Wh	1.8 kJ	-	standard single unit scale
1 Wh	3.6 kJ	-	standard single unit scale
2 Wh	7.2 kJ	-	standard single unit scale
5 Wh	18 kJ	-	multiple unit increments
10 Wh	36 kJ	-	multiple unit increments
25 Wh	90 kJ	-	multiple unit increments
50 Wh	180 kJ	-	multiple unit increments
100 Wh	360 kJ	-	multiple unit increments
250 Wh	900 kJ	-	multiple unit increments
500 Wh	1800 kJ	-	multiple unit increments
1000 Wh	3600 kJ	-	multiple unit increments

Wh to kJ Formula and Examples

Direct Formula kJ = Wh × 3.6

Inverse Formula Wh = kJ × 0.277778

Mental Math Shortcut

Multiply the value by roughly 3.6 to calculate the equivalent amount in your head.

Common Watt-hour to Kilojoule Calculations

5 Wh = 18 kJ
10 Wh = 36 kJ
50 Wh = 180 kJ
100 Wh = 360 kJ
500 Wh = 1800 kJ

Precision & Practical Use

For example, 10 Wh = 36 kJ — roughly multiple unit increments.

Utility bills and appliance ratings are given in whole kWh or BTU. Round converted figures to match the source document you're comparing against.

How to Convert Watt-hour to Kilojoule

How many kilojoules are in one watt-hour?

One Watt-hour (Wh) equals 3.6 Kilojoule (kJ). To convert watt-hours to kilojoules, multiply the watt-hour value by 3.6.

How do I convert Watt-hour to Kilojoule?

Multiply your watt-hour value by 3.6 to get the result in Kilojoule: kJ = Wh × 3.6. For example, 5 Wh = 18 kJ.

What is the formula for converting Wh to kJ?

The conversion formula is kJ = Wh × 3.6. Use the calculator above for any value, and see the reference table below for common inputs from 0.001 to 1000.

Is there a quick mental estimate for Wh to kJ?