Kilojoules (kJ) to Calories (cal) Converter
Enter a value to instantly convert between energy units.
1 Kilojoule = 239.0057 Calorie (thermochemical)
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
cal = kJ × 239.0057One kilojoule equals 239 thermochemical calories. Kilojoules are modern SI units; calories (lowercase 'cal') are legacy chemistry/physics units. Converting kJ to cal is needed when reading or translating historical scientific literature, old lab equipment, or chemistry textbooks published before SI adoption. Note: food 'Calories' (uppercase, kcal) are 1000 times larger.
Source: NIST SP 811, Table B.8
Frequently Asked Questions
Real-World Examples
1 food Calorie (kcal) = 4.184 kJ. 1 kJ = 239 cal. So 1 kcal = 1000 cal = 4.184 kJ (checks out).
4.184 kJ = 1000 cal
Definition: 1 kJ = 239.0057 thermochemical calories (cal) exactly.
1 kJ = 239.01 cal
A 1950s calorimeter study reports 2,390 cal of reaction heat — equivalent to 10 kJ for the modern SI journal.
10 kJ = 2390.06 cal
A combustion experiment in an old lab manual: 11,950 cal of heat release = 50 kJ in modern units.
50 kJ = 11950.28 cal