Convert energy units — joules, kilowatt-hours, calories, BTU, electron volts and more.
| Unit | Name | Value |
|---|---|---|
| 0.001 cal | 4.184e-09 MJ | |
| 0.01 cal | 4.184e-08 MJ | |
| 0.1 cal | 4.184e-07 MJ | |
| 1 cal | 4.184e-06 MJ | |
| 5 cal | 2.092e-05 MJ | |
| 10 cal | 4.184e-05 MJ | |
| 50 cal | 0.0002092 MJ | |
| 100 cal | 0.0004184 MJ | |
| 1000 cal | 0.004184 MJ |
Formula: Megajoule = Calorie × 4.1840e-6
Multiply any calorie value by 4.1840e-6 to get megajoule.
Reverse: Calorie = Megajoule × 239,000
Common calorie values — factor: 1 cal = 4.1840e-6 MJ
| Calorie (cal) | Megajoule (MJ) | Context |
|---|---|---|
| 1 cal | 4.184e-06 MJ | 1 cal |
| 5 cal | 2.092e-05 MJ | 5 cal |
| 10 cal | 4.184e-05 MJ | Small candy |
| 50 cal | 0.0002092 MJ | 50 cal |
| 100 cal | 0.0004184 MJ | Short walk |
| 500 cal | 0.002092 MJ | Snack |
| 1,000 cal | 0.004184 MJ | Light meal |
| 5,000 cal | 0.02092 MJ | Meal |
| 1e+04 cal | 0.04184 MJ | Large meal |
| 5e+04 cal | 0.2092 MJ | Daily intake fraction |
| 1e+05 cal | 0.4184 MJ | 100 kcal |
| 5e+05 cal | 2.092 MJ | 500 kcal workout |
| 1e+06 cal | 4.184 MJ | 1 Mcal |
| 1.000e+09 cal | 4,184 MJ | 1 Gcal |
| 1.000e+12 cal | 4.184e+06 MJ | 1 Tcal |
1 cal = 4.1840e-6 MJ. Memorize for instant estimates.
Use 4.1840e-6 as a quick mental multiplier.
Multiply result by 239,000 to recover the original cal value.
Measures fuel energy content — 1 liter of petrol ≈ 34 MJ.
Compares battery pack energy in MJ and kWh for range calculations.
Quantifies explosive yield — 1 kg TNT ≈ 4.6 MJ.
Calculates daily/annual energy yield of solar and wind in MJ.
Compares fuel energy costs across transport modes in MJ/km.
Models annual heating and cooling energy demand in MJ.
The calorie (cal) was defined in 1824 as the heat needed to raise 1 gram of water by 1°C. There are two versions: the small calorie (cal = 4.184 J) and the large calorie or kilocalorie (kcal = 4,184 J), which is the 'Calorie' used in nutrition.
The calorie remains standard in chemistry for heat of reaction measurements. In the US, food packaging uses 'Calories' (with capital C) which are actually kilocalories — a persistent source of confusion.
Interesting fact: The confusion between cal and kcal means that a food label saying '200 Calories' actually means 200 kcal = 200,000 cal = 836,800 joules. The SI unit for food energy is the kilojoule.
The megajoule (MJ) equals 1,000,000 joules and is used for large-scale energy measurements in engineering, transportation, and industrial processes.
One liter of petrol contains about 34 MJ of chemical energy. A bolt of lightning releases about 1-5 MJ. An adult's daily food intake is roughly 8-10 MJ. Electric vehicle batteries are typically rated at 40-100 MJ (11-28 kWh).
Interesting fact: The kinetic energy of a 1,000 kg car traveling at 100 km/h is about 0.385 MJ. TNT explosive releases about 4.6 MJ per kilogram when detonated.
Converting calorie to megajoule is common across energy, nutrition, engineering, and science. Different sectors use different energy units — joules in physics, kcal in nutrition, kWh in electricity, and BTU in HVAC — making accurate conversion essential for cross-disciplinary work and international comparisons.
Quick reference: 5 cal = 2.0920e-5 MJ and 10 cal = 4.1840e-5 MJ. Reverse: 1 MJ = 239,000 cal. Exact factor: 1 cal = 4.1840e-6 MJ.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.