Watt-hours to Kilojoules Converter
Convert Watt-hours (Wh) to Kilojoules (kJ) instantly, or use the conversion table below to look up common values.
Watt-hours to Kilojoules conversion table
| Watt-hours (Wh) | Kilojoules (kJ) |
|---|---|
| 1 | 3.6 |
| 2 | 7.2 |
| 3 | 10.8 |
| 4 | 14.4 |
| 5 | 18 |
| 10 | 36 |
| 25 | 90 |
| 50 | 180 |
| 100 | 360 |
How to convert Watt-hours to Kilojoules
1 Wh equals 3.6 kJ. Use the converter above for any value, or read the table for common conversions.
kJ = Wh × 3.6 · Wh = kJ × 0.2777777777777778Multiply a watt-hours figure by 3.6 to get kilojoules, or divide it by 0.277778 to go the other way.
Worked examples
- 1 Wh= 3.6 kJ
- 5 Wh= 18 kJ
- 10 Wh= 36 kJ
- 100 Wh= 360 kJ
- 500 Wh= 1,800 kJ
What these units are
Watt-hours (Wh). A watt-hour is the energy of one watt sustained for one hour — 3,600 joules. It is used for battery and power-bank capacity; a phone battery is typically 10 to 20 watt-hours.
Kilojoules (kJ). A kilojoule is 1,000 joules. It is used for food energy in most countries outside the United States, and for small industrial figures.
All factors are exact definitions, so only the display is rounded.
Converting Watt-hours to Kilojoules in practice
Reading the result in kilojoules
One kilojoule is exactly 1,000 joules, and the symbol is kJ. It is the joule multiple that food packaging commonly prints, with energy shown in kilojoules beside kilocalories, and chemistry uses it for reaction energies.
Nutrition panels, exercise machines and dietary advice report energy in kilojoules wherever the metric system is used. Materials and fuel data, such as energy content per kilogram, are tabulated in kilojoules as well.
The step from kilojoules to megajoules divides by exactly one thousand, so nothing is lost in the conversion. One kilocalorie equals 4.184 kilojoules, which is how the two columns on a food label correspond.
A reader who compares a kilojoule figure with a kilocalorie figure as though they were the same number will misjudge the energy by more than four times. The label's two columns state one amount in two units.
Kilojoules and kilocalories are the two energy columns on a food label, and the kilojoule figure is the larger number because one kilocalorie is 4.184 kilojoules. Megajoules take over where kilojoule figures become long, as they do for fuels.
Checking a watt-hours to kilojoules conversion
Energy units are defined against the joule, so every conversion in this dimension is a single exact multiplication by a published number rather than a chain of steps that could accumulate error.
The pair that needs care is the kilowatt-hour, because it looks like a power unit and is not. It is a watt sustained for an hour, which is why an electricity meter counts in kilowatt-hours while a generator is rated in kilowatts: one is an amount, the other is a rate, and only a duration links them.
To check an energy conversion, express both sides in joules or both in kilowatt-hours before comparing. The commonest mistake is treating a food calorie as a calorie when the label means a kilocalorie, which understates the figure a thousandfold.
Tanzania reference points
Real quantities, converted into the units on this page.
One unit of electricity on a Tanzanian prepaid meter
1 kWh = 1,000 Wh = 3,600 kJ
The average domestic rate was about 229.59 TZS per kWh as of December 2025, including taxes and supply. That is an average across domestic customers, not the marginal rate on a bill.
Source: GlobalPetrolPrices — Tanzania electricity prices (compiled from EWURA/TANESCO tariffs) · verified 2026-09-14
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