MJ to Wh — convert megajoules to watt-hours
Exact 1 × 277.777778 = 277.777778
1 megajoule in other units
| Joules | 1,000,000 | J |
|---|---|---|
| Kilojoules | 1,000 | kJ |
| Watt-hours | 277.777778 | Wh |
| Kilowatt-hours | 0.27777778 | kWh |
| Calories | 239,005.74 | cal |
| Kilocalories | 239.005736 | kcal |
| British thermal units | 947.81712 | BTU |
| Therms | 0.009478171203 | thm |
| Foot-pounds | 737,562.15 | ft·lbf |
| Electronvolts | 6,241,509,074,460,762,785,710,080 | eV |
MJ to Wh at a glance
| Megajoules | Watt-hours |
|---|---|
| 1 MJ | 277.777778 Wh |
| 2 MJ | 555.555556 Wh |
| 3 MJ | 833.333333 Wh |
| 5 MJ | 1,388.89 Wh |
| 10 MJ | 2,777.78 Wh |
| 20 MJ | 5,555.56 Wh |
| 25 MJ | 6,944.44 Wh |
| 50 MJ | 13,888.89 Wh |
| 100 MJ | 27,777.78 Wh |
| 250 MJ | 69,444.44 Wh |
| 500 MJ | 138,888.89 Wh |
| 1,000 MJ | 277,777.78 Wh |
How to convert megajoules to watt-hours
Multiply by 277.777778 — one megajoule is 277.777778 watt-hours. That factor is exact: it comes from the definition of the units rather than from a measurement, so it will not change and does not need rounding.
Working 1 × 277.777778 = 277.777778
In words: about two hundred seventy-eight watt-hours.
Questions
How many watt-hours are in a megajoule?
One megajoule is 277.777778 watt-hours. This figure is exact — it comes from the definition of the unit, not a measurement.
What is 1 megajoule in watt-hours?
1 megajoule is 277.777778 watt-hours. The working is 1 × 277.777778 = 277.777778.
Is a food Calorie the same as a calorie?
No — it is a thousand of them. The Calorie on a nutrition label is a kilocalorie, written with a capital C in principle and almost never in practice. A 250 Calorie chocolate bar holds 250,000 physics calories, or about 1,046 kilojoules, which is why European labels quote kJ alongside.
What does a kilowatt-hour actually represent?
One kilowatt drawn for one hour — a 1,000 W heater running for sixty minutes, or a 100 W bulb for ten hours. It is the unit your electricity bill is priced in, and it equals exactly 3.6 million joules.
How much energy is one BTU?
Roughly the heat needed to raise one pound of water by one degree Fahrenheit — about 1,055 joules, or the energy in a single kitchen match. Air conditioners are rated in BTU per hour, where a 12,000 BTU/h unit is one "ton" of cooling and draws around 3.5 kW of heat.
Why is the electronvolt so small?
Because it is sized for single particles: it is the energy one electron picks up crossing a one-volt potential difference. At about 1.6 × 10⁻¹⁹ joules it would be absurd for anything larger, which is precisely why particle physics uses it instead of dragging around twenty leading zeros.