4.184 Joules to Kilocalories: kcal = J | Home » Math & Conversions » Unit Conversions » Calories to Joules (cal to J) Converter Calories to Joules (cal to J) Converter A 3-way energy converter. Enter a value in any field to instantly convert between **Joules (J)**, **Calories (cal)**, and **Kilocalories (kcal)** (food Calories). Joules (J) Calories (cal) (small/gram) Kilocalories (kcal) (Food Calories/Cal) The Difference: Calorie (cal) vs. Calorie (kcal) The main source of confusion in this conversion is that the word "calorie" is used for two different units of energy. This tool converts both, eliminating the confusion. Calorie (cal): This is the "small calorie" or "gram calorie" used in physics and chemistry. It's the energy needed to raise the temperature of 1 gram of water by 1°C. Kilocalorie (kcal): This is the "large calorie" or "food Calorie" (with a capital C). It's the unit you see on nutrition labels. 1 kcal = 1,000 cal . Conversion Formulas The conversion is based on the international standard for the thermochemical calorie: 1 Calorie (cal) = 4.184 Joules (J) From this, all other conversions are derived: Joules to Calories: cal = J