Joule to Calorie Converter
1 J ≈ 0.239 cal (small) ≈ 0.000239 kcal (food calorie).
Result
Loading calculator…
—
How to use this calculator
- Enter joules.
- Pick output (small cal or food kcal).
- Read converted value.
About this calculator
Inverse of calorie-to-joule. 1 kJ ≈ 239 small cal ≈ 0.239 kcal. Some example energies: a baseball thrown at 90 mph has ~135 J kinetic energy, equivalent to about 32 calories (small) or 0.032 food Calories.
Frequently asked
Is the kcal/Calorie thing really a problem?+
Mostly resolved by context — nutrition uses kcal/Cal, physics uses J or cal. Watch for "calories" (lowercase) on energy bars — usually kcal in disguise.
kJ on lab equipment?+
Yes — physics, chemistry, and engineering all use kJ. Multiply by 0.239 to get small calories.
Quick mental math?+
4 J ≈ 1 small cal. 4 kJ ≈ 1 kcal.
Watt-seconds vs Joules?+
Same thing. 1 W·s = 1 J.
Why might my measurement differ slightly?+
Different "calorie" definitions exist; thermochemical (4.184) is the most common. If you see 4.1868 (IT calorie), you're using a different convention.
Related calculators
Calorie to Joule Converter
1 cal (thermochemical) = 4.184 J. 1 kcal (food calorie) = 4,184 J.
Joule ↔ Electron-Volt Converter
For atomic and particle-physics scales: 1 eV = 1.602176634 × 10⁻¹⁹ J.
Horsepower to Watts Converter
Convert mechanical (imperial) horsepower to watts. 1 hp = 745.7 W.
BTU to kWh Converter
Convert British thermal units to kilowatt-hours. 1 BTU ≈ 0.000293 kWh.
kWh to BTU Converter
Convert kilowatt-hours to BTU. 1 kWh = 3,412 BTU.
Calories Burned by Activity (MET) Calculator
kcal = MET × weight (kg) × hours. Compendium MET values for 14 common activities.