Kilojoules to Joules Converter
Convert Kilojoules (kJ) to Joules (J) instantly, or use the conversion table below to look up common values.
Kilojoules to Joules conversion table
| Kilojoules (kJ) | Joules (J) |
|---|---|
| 1 | 1,000 |
| 2 | 2,000 |
| 3 | 3,000 |
| 4 | 4,000 |
| 5 | 5,000 |
| 10 | 10,000 |
| 25 | 25,000 |
| 50 | 50,000 |
| 100 | 100,000 |
How to convert Kilojoules to Joules
1 kJ equals 1,000 J. Use the converter above for any value, or read the table for common conversions.
J = kJ × 1000 · kJ = J × 0.001Multiply a kilojoules figure by 1,000 to get joules, or divide it by 0.001 to go the other way.
Worked examples
- 1 kJ= 1,000 J
- 5 kJ= 5,000 J
- 10 kJ= 10,000 J
- 100 kJ= 100,000 J
- 500 kJ= 500,000 J
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.
Joules (J). The joule is the SI unit of energy: the work done by one newton over one meter. It is used for small energy amounts in physics and engineering.
All factors are exact definitions, so only the display is rounded.
Converting Kilojoules to Joules 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.
Reading the result in joules
Energy in the International System of Units is measured in joules, where one joule is the work done by a force of one newton moving an object one metre. The symbol is J.
Physics and engineering use the joule for mechanical work, heat, radiation and electrical energy, and small appliance labels sometimes state a surge or pulse rating in joules.
Multiples of the joule such as the kilojoule and megajoule are exact powers of one thousand, so no precision is lost. A watt is a rate rather than an amount, so it must be multiplied by time to yield joules.
The usual slip is to quote an electricity meter reading in joules when the meter counts kilowatt-hours. Both name energy, but the joule figure is 3.6 million times the kilowatt-hour figure.
The joule is the base unit, the kilojoule and megajoule are its decimal multiples, and the kilowatt-hour is the accounting unit an electricity meter counts. Joules suit physics and small quantities, while kilowatt-hours suit billing and storage capacity.
Checking a kilojoules to joules 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 = 3,600,000 J
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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