Convert energy units — joules, calories, kilowatt-hours, BTU, kilojoules.
| Unit | Name | Value |
|---|---|---|
| J | Joule | 1000 |
| cal | Calorie | 239.00574 |
| kcal | Kilocalorie (Cal) | 0.23900574 |
| kWh | Kilowatt-hour | 0.00027777778 |
| BTU | BTU | 0.94781339 |
Formula: Kilocalorie = Kilojoule × 0.239
Multiply any kilojoule value by 0.239 to get kilocalorie.
Reverse: Kilojoule = Kilocalorie × 4.184
Common kilojoule values — factor: 1 kJ = 0.239 kcal
| Kilojoule (kJ) | Kilocalorie (kcal) | Context |
|---|---|---|
| 0.001 kJ | 0.000239 kcal | 1 J |
| 0.01 kJ | 0.00239 kcal | 10 J |
| 0.1 kJ | 0.0239 kcal | 100 J |
| 1 kJ | 0.239 kcal | 1 kJ |
| 4.184 kJ | 1 kcal | 1 kcal |
| 10 kJ | 2.39 kcal | 10 kJ |
| 100 kJ | 23.9 kcal | 100 kJ |
| 1,000 kJ | 239 kcal | 1 MJ |
| 3,600 kJ | 860.4 kcal | 1 kWh |
| 1e+04 kJ | 2,390 kcal | 10 MJ |
| 1e+05 kJ | 2.39e+04 kcal | 100 MJ |
| 1e+06 kJ | 2.39e+05 kcal | 1 GJ |
| 1e+08 kJ | 2.39e+07 kcal | 100 GJ |
| 1.000e+10 kJ | 2.390e+09 kcal | 10 TJ |
| 1.000e+12 kJ | 2.390e+11 kcal | 1 PJ |
kJ ÷ 4.184 = kcal. Round to ÷ 4.2.
One dietary calorie = 4.184 kilojoules.
kcal × 4.184 = kJ.
Labels food energy in kJ for metric-market nutritional information.
Calculates reaction heat, enthalpy changes, and process energy in kJ.
Measures athlete metabolic rate and substrate oxidation in kJ.
Teaches heat transfer, steam tables, and engine cycles using kJ.
Prescribes energy intake using kJ in countries using metric labels.
Calculates heat duty for reactors, heat exchangers, and distillation in kJ.
The kilojoule (kJ) equals 1,000 joules and is the practical energy unit for food, chemistry, and heating applications in metric countries. Food energy labels in Australia, Europe, and most of the world use kilojoules.
A dietary calorie (kcal) equals 4.184 kJ. A can of soda contains about 600 kJ. The specific heat of water (4.184 kJ/kg·°C) means heating 1 liter of water by 1°C requires 4.184 kJ.
Interesting fact: An average adult needs about 8,000-10,000 kJ (2,000-2,400 kcal) per day. Running a marathon burns approximately 12,500 kJ.
The kilocalorie (kcal) equals 1,000 calories or 4,184 joules, and is the unit used on food labels worldwide (often written as 'Cal' with a capital C in the US). It was standardized by the International Table calorie in 1956.
Nutritionists, dietitians, and food scientists use kcal for daily energy intake recommendations. Most adults need 2,000–2,500 kcal/day. Exercise apps, fitness trackers, and dietary plans all operate on kcal.
Interesting fact: One gram of fat yields about 9 kcal, one gram of carbohydrate or protein yields about 4 kcal. A single sugar cube (4g) contains about 16 kcal.
Converting kilojoule to kilocalorie 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 kJ = 1.195 kcal and 10 kJ = 2.39 kcal. Reverse: 1 kcal = 4.184 kJ. Exact factor: 1 kJ = 0.239 kcal.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.