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Free Calories (kcal) to Kilojoules Converter

Convert food calories (kcal) to kilojoules (kJ) — useful when a recipe or US/UK label lists Calories but you need the kilojoules shown on many international labels.

1 kcal = 4.18 kJ

Pick any units and edit either box — it converts instantly in your browser.

Quick answer

To convert calories (kcal) to kilojoules, multiply by 4.184, since one food calorie equals 4.184 kilojoules. For example, 200 kcal is about 836.8 kJ.

Formula & method

kilojoules = calories (kcal) × 4.184
  • kcal — value in calories (kcal)
  • kJ — result in kilojoules
  • 4.184 — exact conversion factor (1 kcal = 4.184 kJ)

To convert back, divide by 4.184 (1 kJ = 0.239006 kcal).

Calories (kcal) to Kilojoules — common values

Calories (kcal) (kcal)Kilojoules (kJ)
50 kcal209.2 kJ
100 kcal418.4 kJ
200 kcal836.8 kJ
250 kcal1,046 kJ
500 kcal2,092 kJ
1,000 kcal4,184 kJ
2,000 kcal8,368 kJ
2,500 kcal10,460 kJ

Examples

Example 1: A small snack
Input
100 kcal
Result
418.4 kJ
Why
About the energy in a small piece of fruit.
Example 2: A typical serving
Input
250 kcal
Result
1,046 kJ
Why
Many single servings sit around 100–300 kcal.
Example 3: A light meal
Input
500 kcal
Result
2,092 kJ
Why
Roughly a quarter of a typical daily intake.
Example 4: A full day's energy
Input
2,000 kcal
Result
8,368 kJ
Why
A common daily reference of 2,000 kcal equals about 8,368 kJ.

Common mistakes

  • Mixing up unit definitions — Uses the food calorie (kcal): 1 kcal = 4.184 kJ.
  • Rounding too early. Multiply by the full factor (4.184) first, then round only the final kilojoules value.
  • Converting the wrong way. This page goes Calories (kcal) → Kilojoules; to go back, divide by 4.184.

Frequently asked questions

What is the exact kcal to kJ factor?

1 kcal = 4.184 kJ (the food/thermochemical calorie). To go from kilocalories to kilojoules, multiply the kilocalories by 4.184.

Is the food 'Calorie' the same as a kcal?

Yes. The capital-C Calorie used on food labels is a kilocalorie (kcal), so a 500-Calorie meal is 500 kcal, or about 2,092 kJ.

How many kilojoules are in 2000 calories?

About 8,368 kJ (2000 × 4.184). That is why a '2,000 kcal' daily reference is often shown as '8,400 kJ' on labels.

Why convert calories to kilojoules?

Kilojoules are the metric (SI) energy unit used on labels in Australia, New Zealand, and the EU, so converting lets you compare a kcal figure with those labels.

Does it matter which calorie definition is used?

For food, the kilocalorie at 4.184 kJ is the standard, and it matches the dual figures printed on nutrition labels, so the result is reliable for everyday use.

Sources & references

External references open in a new tab. We are independent and not affiliated with these organizations.

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