kcal to kJ Converter

Convert kcal to kJ

To convert kcal to kJ, multiply the value in kcal by 4.184. It is used to read Australian and European food labels, sports nutrition data and diet plans written in kilojoules. This kcal to kj converter works both ways: type kcal or kJ into either box above and the other box, the worked formula and the chart below update as you type.

The kilocalorie (kcal) is the energy needed to warm one kilogram of water by about 1 °C. The “Calorie” with a capital C on food labels is the same thing as a kilocalorie. Nutrition labels in the US, UK and India show kcal, and most diet and fitness apps count calories in kcal. One kilocalorie is 4.184 kilojoules.

The kilojoule (kJ) is 1,000 joules. The joule, named after the physicist James Prescott Joule, is the SI unit of energy. Going the other way, one kilojoule equals 0.239006 kilocalories. Australia and New Zealand label food energy in kilojoules, and EU labels show kJ next to kcal.

How to convert kcal to kj with this tool

1. Type a number into the Kilocalories (kcal) box — it starts at 2,000 kcal as an example.
2. Read the answer in the Kilojoules (kJ) box and in the result panel, which also shows the formula with your number.
3. To go the other way, type into the kJ box, or press the swap button to open the kJ to kcal converter with your value carried over.
4. Choose how many decimal places you want, or tap a quick value such as 100 kcal, 250 kcal, 500 kcal.
5. Press Copy result to paste the conversion into a message, spreadsheet or note.

kcal to kJ converter features

kcal to kJ formula

The formula is kJ = kcal × 4.184. It is exact because the thermochemical kilocalorie used for food energy is defined as exactly 4.184 kJ.

The reverse formula is kcal = kJ ÷ 4.184 — or use the kJ to kcal converter. Three worked examples:

• A 2,000 kcal daily intake: 2,000 kcal × 4.184 = 8,368 kJ
• A 250 kcal snack bar: 250 kcal × 4.184 = 1,046 kJ
• 100 kcal of fruit: 100 kcal × 4.184 = 418.4 kJ

kcal to kJ quick reference

The values people look up most often, worked out with the exact factor:

• 1 kcal = 4.184 kJ
• 1 kJ = 0.239006 kcal
• 100 kcal = 418.4 kJ
• 250 kcal = 1,046 kJ
• 500 kcal = 2,092 kJ
• 1,000 kcal = 4,184 kJ

Quick tip: Multiply by 4 and add about 5%: 500 kcal → 2,000 + 100 = 2,100 kJ, close to the exact 2,092 kJ.

Related conversions: the full energy converter.

kcal to kJ conversion table

Values in kJ are rounded to 2 decimal places (more for very small numbers). For any value not listed, type it into the converter above.