Kilocalories (kcal) to Kilojoules (kJ) Converter
Enter a value to instantly convert between energy units.
1 Kilocalorie = 4.184 Kilojoule
Key Formulas
Kilocalorie → Kilojoule
kJ = kcal × 4.184Kilojoule → Kilocalorie
kcal = kJ × 0.239006Kilowatt-Hour → Joule
J = kWh × 3600000Joule → Kilowatt-Hour
kWh = J × 2.77778e-7Formula
kJ = kcal × 4.184Food calories (kcal) are used on nutrition labels in the US. Kilojoules (kJ) are the SI unit; EU and UK labels show kJ alongside kcal, and Australian labels use kJ. The calorie unit was originally defined as the energy to heat 1 gram of water by 1°C. One food 'Calorie' (with capital C) is actually 1 kilocalorie (kcal). For the reverse conversion, see kilojoules to kilocalories.
Source: ISO 80000-5:2019 (Quantities and units—Thermodynamics)
Reviewed by the Convert Calc editorial team · Last reviewed: · see our methodology
Frequently Asked Questions
Real-World Examples
A 200 kcal snack on a US label is about 837 kJ on an EU or Australian label.
200 kcal = 837 kJ
Lunch meal energy. A balanced lunch (sandwich + fruit + drink) is roughly 500-700 kcal, or 2,100-2,900 kJ.
500 kcal = 2092 kJ
Daily caloric intake. 2,000 kcal is the reference daily intake on US nutrition labels. Internationally: 8,400 kJ.
2000 kcal = 8368 kJ
Definition. By scientific definition, 1 food calorie (kcal) = 4,184 joules = 4.184 kJ.
1 kcal = 4.184 kJ