How to Convert Calories to Kilojoules (kJ)

The units of energy can be expressed in calories or kilojoules. To convert calories to kilojoules, multiply by a conversion factor as described here.

You will need

  • Energy unit type
  • Calculator

Step 1 Identify unit usage Determine whether the number of calories refers to food calories or scientific calories. Nutritionists and physical scientists use the terms differently.

Step 2 Convert food calories Multiply food calories by 4.184 to convert calories to kilojoules.

Step 3 Convert scientific calories Multiply scientific calories by 4.184 to convert calories to joules. One joule equal one 1/1000 kilojoules.