100 J to MJ — 100 joules in megajoules
Exact 100 ÷ 1,000,000 = 0.0001
100 joules in other units
| Kilojoules | 0.1 | kJ |
|---|---|---|
| Megajoules | 0.0001 | MJ |
| Watt-hours | 0.02777778 | Wh |
| Kilowatt-hours | 0.000027777778 | kWh |
| Calories | 23.900574 | cal |
| Kilocalories | 0.02390057 | kcal |
| British thermal units | 0.09478171 | BTU |
| Therms | 9.4782e-7 | thm |
| Foot-pounds | 73.756215 | ft·lbf |
| Electronvolts | 624,150,907,446,076,243,968 | eV |
J to MJ at a glance
| Joules | Megajoules |
|---|---|
| 1 J | 0.000001 MJ |
| 2 J | 0.000002 MJ |
| 3 J | 0.000003 MJ |
| 5 J | 0.000005 MJ |
| 10 J | 0.00001 MJ |
| 20 J | 0.00002 MJ |
| 25 J | 0.000025 MJ |
| 50 J | 0.00005 MJ |
| 100 J | 0.0001 MJ |
| 250 J | 0.00025 MJ |
| 500 J | 0.0005 MJ |
| 1,000 J | 0.001 MJ |
How to convert joules to megajoules
Multiply by 0.000001 — one joule is 0.000001 megajoules. 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 100 ÷ 1,000,000 = 0.0001
What these units are
The joule and the megajoule are covered in the energy unit guide, along with every other unit on this page.
Questions
How many megajoules are in a joule?
One joule is 0.000001 megajoules. This figure is exact — it comes from the definition of the unit, not a measurement.
What is 100 joules in megajoules?
100 joules is 0.0001 megajoules. The working is 100 ÷ 1,000,000 = 0.0001.
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.