Kilocalories to Kilojoules

A kilocalorie (kcal), often called a dietary Calorie with a capital C, is a unit of energy used for food and metabolism. A kilojoule (kJ) is the SI unit of energy, and the conversion factor 4.184 comes from the defined relationship between these two units: 1 kcal = 4.184 kJ. Because the factor is fixed, you can convert any food energy value from kcal to kJ by multiplying by 4.184.

Use this formula when reading or comparing nutrition labels that list energy in different units, especially if you need to match the units used in your textbook, country, or diet plan. It is also useful in food science, nutrition calculations, and meal-tracking apps that switch between Calories and kilojoules.

• Mixing up kilocalories (kcal) with small calories (cal) and using the wrong conversion factor
• Dividing by 4.184 instead of multiplying when converting from kcal to kJ
• Rounding too early, which can give a noticeably different final result