Megajoules Converter
Convert Megajoules (MJ) 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 megajoules convert to
One MJ in every other energy unit.
| Unit | 1 MJ | Reverse |
|---|---|---|
| Joules | 1,000,000 J | 1e-6 MJ |
| Kilojoules | 1,000 kJ | 0.001 MJ |
| Watt-hours | 277.777778 Wh | 0.0036 MJ |
| Kilowatt-hours | 0.277778 kWh | 3.6 MJ |
| Calories | 239,005.736138 cal | 4.184e-6 MJ |
| Kilocalories | 239.005736 kcal | 0.004184 MJ |
| BTU | 947.81712 BTU | 0.001055 MJ |
Multiply a megajoules 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.
Megajoules conversion reference
Megajoules to Joules
One megajoules is 1,000,000 joules, and one joules is 1e-6 megajoules.
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 MJ= 1,000,000 J
- 5 MJ= 5,000,000 J
- 10 MJ= 10,000,000 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.
Megajoules to Kilojoules
One megajoules is 1,000 kilojoules, and one kilojoules is 0.001 megajoules.
A kilojoule is 1,000 joules. It is used for food energy in most countries outside the United States, and for small industrial figures.
- 1 MJ= 1,000 kJ
- 5 MJ= 5,000 kJ
- 10 MJ= 10,000 kJ
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.
Megajoules to Watt-hours
One megajoules is 277.777778 watt-hours, and one watt-hours is 0.0036 megajoules.
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 MJ= 277.777778 Wh
- 5 MJ= 1,388.888889 Wh
- 10 MJ= 2,777.777778 Wh
Megajoules to Kilowatt-hours
One megajoules is 0.277778 kilowatt-hours, and one kilowatt-hours is 3.6 megajoules.
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 MJ= 0.277778 kWh
- 5 MJ= 1.388889 kWh
- 10 MJ= 2.777778 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.
Megajoules to Calories
One megajoules is 239,005.736138 calories, and one calories is 4.184e-6 megajoules.
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 MJ= 239,005.736138 cal
- 5 MJ= 1,195,028.680688 cal
- 10 MJ= 2,390,057.361377 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.
Megajoules to Kilocalories
One megajoules is 239.005736 kilocalories, and one kilocalories is 0.004184 megajoules.
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 MJ= 239.005736 kcal
- 5 MJ= 1,195.028681 kcal
- 10 MJ= 2,390.057361 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.
Megajoules to BTU
One megajoules is 947.81712 btu, and one btu is 0.001055 megajoules.
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 MJ= 947.81712 BTU
- 5 MJ= 4,739.085602 BTU
- 10 MJ= 9,478.171203 BTU
What megajoules are used for
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.
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.
Multiplying a power figure in kilowatts by a duration in seconds produces joules, and a thousand of those make one megajoule. One kilowatt-hour is exactly 3.6 megajoules, the same energy under another name.
The frequent confusion is to treat a megawatt of capacity as a megawatt-hour of energy, and the same slip appears with megajoules when a rate is read as an amount. Time is the missing factor.
Megajoules and kilojoules differ only by a factor of one thousand, while the kilowatt-hour names the same energy at exactly 3.6 megajoules. Fuel data is tabulated in megajoules, electricity accounting uses kilowatt-hours, and mechanics works in joules.
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 megajoules.
One unit of electricity on a Tanzanian prepaid meter
1 kWh = 3.6 MJ
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
Megajoules conversion tables
Megajoules to Joules
| Megajoules (MJ) | Joules (J) |
|---|---|
| 1 | 1,000,000 |
| 2 | 2,000,000 |
| 3 | 3,000,000 |
| 4 | 4,000,000 |
| 5 | 5,000,000 |
| 10 | 10,000,000 |
| 25 | 25,000,000 |
| 50 | 50,000,000 |
| 100 | 100,000,000 |
Megajoules to Kilojoules
| Megajoules (MJ) | Kilojoules (kJ) |
|---|---|
| 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 |
Megajoules to Watt-hours
| Megajoules (MJ) | Watt-hours (Wh) |
|---|---|
| 1 | 277.777778 |
| 2 | 555.555556 |
| 3 | 833.333333 |
| 4 | 1,111.111111 |
| 5 | 1,388.888889 |
| 10 | 2,777.777778 |
| 25 | 6,944.444444 |
| 50 | 13,888.888889 |
| 100 | 27,777.777778 |