Calorie to Joule Converter

1 cal (thermochemical) = 4.184 J. 1 kcal (food calorie) = 4,184 J.

Inputs

Result

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General calculation reads

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How to use this calculator

  • Enter calories.
  • Pick small or food (kcal).
  • Read joules / kJ.

About this calculator

Note the capital-C confusion: "calorie" usually means SMALL calorie (4.184 J), but "Calorie" with a capital C and "food calorie" mean kilocalorie (4,184 J). A 200-Calorie cookie is 200 kcal = 836 kJ, the same energy as a 200 W appliance running for ~1 hour.

Frequently asked

Calorie vs Calorie?+
In nutrition, "Calorie" (capital C) = kilocalorie. In physics, "calorie" (lowercase) = small calorie. Be explicit when conversions are involved.
How many joules in a Twinkie?+
A 150-Calorie Twinkie = 150 kcal × 4184 = 627,600 J = 628 kJ.
kJ on European nutrition labels?+
Yes — EU labels show kJ alongside kcal. 1 kcal = 4.184 kJ.
Multiple "calorie" definitions?+
Thermochemical (4.184), 15°C (4.1855), IT (4.1868), 4°C (4.204). Differences <0.5%; use thermochemical for most conversions.
How does this relate to BTU?+
1 BTU ≈ 252 small calories ≈ 0.252 kcal. 1 kcal ≈ 3.97 BTU.

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