Convert Kilocalorie to Kilojoule (kcal → kJ)
The kilocalorie (called Calorie on US food labels) measures dietary energy in nutrition worldwide.
Kilocalorie to Kilojoule Conversion Table
10 common values| Kilocalorie | Kilojoule |
|---|---|
| 1 kcal | 4.184 kJ |
| 10 kcal | 41.84 kJ |
| 100 kcal | 418.4 kJ |
| 500 kcal | 2,092 kJ |
| 1,000 kcal | 4,184 kJ |
| 5,000 kcal | 20,920 kJ |
| 10,000 kcal | 41,840 kJ |
| 50,000 kcal | 209,200 kJ |
| 100,000 kcal | 418,400 kJ |
| 500,000 kcal | 2,092,000 kJ |
How to Convert Kilocalorie to Kilojoule Manually
Step by StepConverting kilocalories to kilojoules is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.
- 1Take your value in kilocaloriesStart with the number of kilocalories (kcal) you want to convert.
- 2Multiply by 4.184The conversion factor from kcal to kJ is 4.184. Multiply your value by this number.
- 3Read the result in kilojoulesThe result is your value in kilojoules (kJ).
Formula
Multiply the value in kilocalories by 4.184. For the reverse direction, multiply by 0.239006.
kJ = kcal × 4.184kcal = kJ × 0.239006Tips
Use these in everyday conversions- 1 kcal = 4.184 kJ.
- US "Calorie" (with capital C) = 1 kcal.
- Apps and smartwatches track active energy in kcal.
Common Mistakes
Avoid these- Reading food "Calories" as gram calories — factor of 1000 off.
- Treating all calorie values as comparable — macros (fat, protein, carb) differ in energy density.
- Counting kcal without portion size leads to underestimates.
About Kilocalorie and Kilojoule
What is the Kilocalorie?
The kilocalorie equals 1,000 small calories or exactly 4.184 kilojoules and is the universal unit for measuring dietary energy in food. Confusingly, on US food labels and in popular usage, 'Calorie' (capital C) means kilocalorie — so a 200-Calorie cookie is actually 200,000 small calories, or 200 kcal. This convention dates to American chemist Wilbur Atwater's 19th-century nutrition research. Recommended daily intake is roughly 2,000 kcal for women and 2,500 kcal for men. The kilocalorie remains the everyday food-energy unit in the United States, while European labels show both kJ and kcal. Athletes track caloric burn during exercise in kcal: running burns about 100 kcal per mile. The kcal relates to the kilojoule (4.184 kJ = 1 kcal), the joule (1 kcal = 4,184 J), and the BTU (1 BTU ≈ 0.252 kcal). Marathon runners burn roughly 2,600 kcal during a 42-km race.
- Nutrition labels worldwide
- Diet and weight-management tracking
- Dietetics and clinical nutrition
Adult daily intake: ~2000 kcal. Banana: 90 kcal. Big Mac: 550 kcal. 30 min running: ~300 kcal burned.
What is the Kilojoule?
The kilojoule equals 1,000 joules and is the standard unit on European nutrition labels and in mid-scale chemical and physical calculations. EU regulations require food packaging to display energy in kilojoules (typically with kilocalories also shown for consumer familiarity): a chocolate bar might show '2,100 kJ / 500 kcal' per 100 g. The kilojoule is also common in chemistry (bond energies), electrical engineering (capacitor storage), and small-mechanical-energy contexts. A car battery typically stores about 1,800 kJ; lifting a person 1 meter requires roughly 0.7 kJ. The kilojoule relates to the joule (1,000 J = 1 kJ), the kilocalorie (1 kcal = 4.184 kJ), the watt-hour (1 kWh = 3,600 kJ), and the megajoule (1,000 kJ = 1 MJ). The conversion factor 4.184 (kJ per kcal) is one of the most-used numbers in nutrition labeling.
- EU and UK nutrition labels
- Mechanical work in engineering
- Battery capacity in vehicles
100 g chocolate: ~2100 kJ. EU daily intake (adult): ~8400 kJ. Tesla Model 3 battery: ~270 MJ = 270,000 kJ.