Convert Kilojoule to Kilocalorie (kJ → kcal)

Converting kilojoules to kilocalories is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in kilojoules

   Start with the number of kilojoules (kJ) you want to convert.
2. 2
   Multiply by 0.239006

   The conversion factor from kJ to kcal is 0.239006. Multiply your value by this number.
3. 3
   Read the result in kilocalories

   The result is your value in kilocalories (kcal).

Multiply the value in kilojoules by 0.239006. For the reverse direction, multiply by 4.184.

• ✓1 kJ = 1000 J = 0.239 kcal.
• ✓EU nutrition labels must show both kJ and kcal.
• ✓For quick conversion: kcal × 4.2 = kJ.

• ✗Assuming European labels use kcal only — they use both kJ and kcal.
• ✗Confusing kJ with kW (power).
• ✗Using kcal when kJ is requested in scientific context.

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

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