Kilojoules Converter
Convert Kilojoules (kJ) to any other energy unit. The table below gives the exact figure for each unit, and every conversion is worked from the same engine as the converter.
What kilojoules convert to
One kJ in every other energy unit.
| Unit | 1 kJ | Reverse |
|---|---|---|
| Joules | 1,000 J | 0.001 kJ |
| Megajoules | 0.001 MJ | 1,000 kJ |
| Watt-hours | 0.277778 Wh | 3.6 kJ |
| Kilowatt-hours | 2.7778e-4 kWh | 3,600 kJ |
| Calories | 239.005736 cal | 0.004184 kJ |
| Kilocalories | 0.239006 kcal | 4.184 kJ |
| BTU | 0.947817 BTU | 1.055056 kJ |
Multiply a kilojoules figure by the figure in the second column to get the unit in the first, or multiply by the third column to go the other way.
Kilojoules conversion reference
Kilojoules to Joules
One kilojoules is 1,000 joules, and one joules is 0.001 kilojoules.
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.
- 1 kJ= 1,000 J
- 5 kJ= 5,000 J
- 10 kJ= 10,000 J
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.
Kilojoules to Megajoules
One kilojoules is 0.001 megajoules, and one megajoules is 1,000 kilojoules.
A megajoule is 1,000 kilojoules, or about 0.278 kilowatt-hours. It is used for the energy content of fuels: a litre of diesel holds roughly 36 megajoules.
- 1 kJ= 0.001 MJ
- 5 kJ= 0.005 MJ
- 10 kJ= 0.01 MJ
One megajoule is 1,000 kilojoules, which is one million joules. Fuels, industrial processes and large energy figures are quoted in megajoules when a count in joules would be unwieldy.
Fuel energy content, blast energy, industrial process heat and large-scale storage are described in megajoules. Engineering calculations for combustion and materials testing also use the unit.
Kilojoules to Watt-hours
One kilojoules is 0.277778 watt-hours, and one watt-hours is 3.6 kilojoules.
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.
- 1 kJ= 0.277778 Wh
- 5 kJ= 1.388889 Wh
- 10 kJ= 2.777778 Wh
Kilojoules to Kilowatt-hours
One kilojoules is 2.7778e-4 kilowatt-hours, and one kilowatt-hours is 3,600 kilojoules.
A kilowatt-hour is 1,000 watt-hours, or 3.6 megajoules. It is the unit on electricity bills, and the 'unit' shown on a prepaid meter.
- 1 kJ= 2.7778e-4 kWh
- 5 kJ= 0.001389 kWh
- 10 kJ= 0.002778 kWh
The kilowatt-hour is the energy of one kilowatt sustained for one hour, and it is exactly 3.6 megajoules. Its symbol is kWh, and it equals 1,000 watt-hours.
Electricity bills, prepaid meter units, solar generation totals and battery or power-bank capacity are all measured in kilowatt-hours. Appliance consumption over time is compared in the same unit.
Kilojoules to Calories
One kilojoules is 239.005736 calories, and one calories is 0.004184 kilojoules.
A calorie here is the small calorie of 4.184 joules — the energy needed to raise one gram of water by one degree Celsius. Food labels use the kilocalorie, which is 1,000 of these.
- 1 kJ= 239.005736 cal
- 5 kJ= 1,195.028681 cal
- 10 kJ= 2,390.057361 cal
One thermochemical calorie is exactly 4.184 joules, a definition fixed by convention rather than by a water experiment. The food calorie on a nutrition label is a kilocalorie of 4,184 joules.
The small calorie appears in chemistry, physics and heat-capacity problems, where a substance's specific heat is expressed per gram per degree. Nutrition labels use the much larger food calorie instead.
Kilojoules to Kilocalories
One kilojoules is 0.239006 kilocalories, and one kilocalories is 4.184 kilojoules.
A kilocalorie is 1,000 calories, or 4,184 joules. It is the 'calorie' on food labels, so a 2,000-calorie diet means 2,000 kilocalories.
- 1 kJ= 0.239006 kcal
- 5 kJ= 1.195029 kcal
- 10 kJ= 2.390057 kcal
Exactly 1,000 thermochemical calories, or 4,184 joules, make one kilocalorie. A food label that prints calorie, often with a capital letter, means this unit rather than the small calorie of physics.
Food energy on packaging, diet plans, restaurant menus and sports nutrition is stated in kilocalories. Physiology and nutrition research also reports energy expenditure in the same unit.
Kilojoules to BTU
One kilojoules is 0.947817 btu, and one btu is 1.055056 kilojoules.
A BTU (British thermal unit) is 1,055.05585262 joules — the energy needed to heat one pound of water by one degree Fahrenheit. It is used for heating and cooling capacity.
- 1 kJ= 0.947817 BTU
- 5 kJ= 4.739086 BTU
- 10 kJ= 9.478171 BTU
What kilojoules are used for
A kilojoule is 1,000 joules. It is used for food energy in most countries outside the United States, and for small industrial figures.
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.
All factors are exact definitions, so only the display is rounded.
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 kilojoules.
One unit of electricity on a Tanzanian prepaid meter
1 kWh = 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
Kilojoules conversion tables
Kilojoules to Joules
| 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 |
Kilojoules to Megajoules
| Kilojoules (kJ) | Megajoules (MJ) |
|---|---|
| 1 | 0.001 |
| 2 | 0.002 |
| 3 | 0.003 |
| 4 | 0.004 |
| 5 | 0.005 |
| 10 | 0.01 |
| 25 | 0.025 |
| 50 | 0.05 |
| 100 | 0.1 |
Kilojoules to Watt-hours
| 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 |