How many Calories are in one kiloJoule? Thermochemical Calories. 1 kJ = 239.0057 cal th. 15ºC calories. 1 kJ = 238.9201 cal 15. Large/food calories. 1 kJ =0.239 Cal. Kilojoules8,700. The conversion factor between a kilojoule (kJ) and a calorie (also called kilocalorie, kcal, or Cal) is 0.239, because each calorie contains 4.184 kilojoules. To do the reverse operation (convert calories to kilojoules), use the calculator below this one: Here is the answer to converting 400 kJ to calories, along with the kJ to kcal formula and the math: kJ × 0.23900574 = Calories. 400 × 0.23900574 = 95.602296. 400 kJ ≈ 96 calories. kJ to Cal Converter. 400 kJ to calories is not all we can convert for you. Here you can enter another kilojoules (kJ) measurement that we can convert to calories HpCfbyy.