Calories (cal) to Joules (J) Converter
Enter a value to instantly convert between energy units.
1 Calorie (thermochemical) = 4.184 Joule
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
J = cal × 4.184One thermochemical calorie equals exactly 4.184 joules by definition. This unit, distinct from the large dietary Calorie (kcal), is used in chemistry and physics for heat measurements and food energy calculations in scientific literature. Understanding this conversion is essential for reconciling nutritional data with SI-based scientific work and comparing historical calorimetry measurements with modern research. For dietary Calories, see [kilocalories to kilojoules](/energy/kcal-to-kj/).
Source: NIST SP 811, Table B.8
Frequently Asked Questions
Real-World Examples
A chemistry experiment measuring 100 cal of heat from a reaction records 418.4 J in the lab notebook.
100 cal = 418.4 J
A nutrition database entry of 1000 cal (1 dietary Calorie or kcal) converts to 4184 J for SI compliance.
1000 cal = 4184 J
Food scientist measuring 239 cal per gram (typical carbohydrate) = 1000 J/g for macronutrient analysis.
239 cal = 999.776 J
Chemistry lab temperature rise experiment: adding 50 cal to water = 209 J thermal energy.
50 cal = 209.2 J