Kilojoules to Watt-hours Converter
Convert Kilojoules (kJ) to Watt-hours (Wh) instantly, or use the conversion table below to look up common values.
Kilojoules to Watt-hours conversion table
| Kilojoules (kJ) | Watt-hours (Wh) |
|---|---|
| 1 | 0.277778 |
| 2 | 0.555556 |
| 3 | 0.833333 |
| 4 | 1.111111 |
| 5 | 1.388889 |
| 10 | 2.777778 |
| 25 | 6.944444 |
| 50 | 13.888889 |
| 100 | 27.777778 |
How to convert Kilojoules to Watt-hours
1 kJ equals 0.277778 Wh. Use the converter above for any value, or read the table for common conversions.
Wh = kJ × 0.2777777777777778 · kJ = Wh × 3.6Multiply a kilojoules figure by 0.277778 to get watt-hours, or divide it by 3.6 to go the other way.
Worked examples
- 1 kJ= 0.277778 Wh
- 5 kJ= 1.388889 Wh
- 10 kJ= 2.777778 Wh
- 100 kJ= 27.777778 Wh
- 500 kJ= 138.888889 Wh
What these units are
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.
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.
All factors are exact definitions, so only the display is rounded.
Converting Kilojoules to Watt-hours in practice
Working 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 kilojoules to watt-hours 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 = 3,600 kJ = 1,000 Wh
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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