This converter turns kilocalories into kilojoules instantly, using the exact factor 1 kilocalorie = 4.184 kilojoules. Type any number and the result updates as you go — nothing is sent to a server, so the arithmetic happens entirely in your browser.
The dietary Calorie shown on US nutrition labels. The food-energy unit on labels outside the United States.
Because the relationship is a simple proportion, one multiplication does the whole job. The table further down gives pre-computed values for the amounts people look up most often, and the result panel also reports the reverse conversion so you can check the figure both ways.
The formula
kilocalories- The amount you are converting, measured in kilocalories
4.184- The exact number of kilojoules in one kilocalorie
kilojoules- The converted result
How it works, step by step
- Enter the number of kilocalories you want to convert.
- The value is multiplied by 4.184, the exact conversion factor.
- The result is displayed in kilojoules, rounded for readability.
- The unrounded value and the reverse conversion appear underneath so you can verify it.
Worked examples
Converting 5 kilocalories
Multiply 5 by 4.184. That gives 20.92 kilojoules. A quick sanity check: one kilocalorie is larger than one kilojoule, so the number should get bigger — and it does.
Converting 72 kilocalories
72 × 4.184 = 301.248 kilojoules. Working backwards, 301.248 ÷ 4.184 returns 72 kilocalories, which confirms the factor is applied the right way round.
How to read your score
Frequently asked questions
How many kilojoules are in one kilocalorie?
Exactly 4.184. Every conversion on this page is that single number multiplied by your input, so the result carries no rounding error beyond what is shown.
What is the formula to convert kilocalories to kilojoules?
Kilojoules = kilocalories × 4.184. To reverse it, divide instead: kilocalories = kilojoules ÷ 4.184, which is the same as multiplying by 0.2390057361.
Is the kilocalorie bigger than the kilojoule?
Yes. One kilocalorie equals 4.184 kilojoules, so it is the larger unit.
Why does my answer differ slightly from other kilocalories to kilojoules converters?
Most differences come from rounding the factor too early. This tool keeps full double precision through the calculation and only rounds at the final display step, and it also shows the unrounded value so you can see exactly where any difference appears.
What is a kilocalorie?
The dietary Calorie shown on US nutrition labels.
What is a kilojoule?
The food-energy unit on labels outside the United States.
Kilocalories to kilojoules reference table
| Kilocalories | Kilojoules |
|---|---|
| 0.5 kcal | 2.092 kJ |
| 1 kcal | 4.184 kJ |
| 2 kcal | 8.368 kJ |
| 3 kcal | 12.552 kJ |
| 5 kcal | 20.92 kJ |
| 10 kcal | 41.84 kJ |
| 15 kcal | 62.76 kJ |
| 20 kcal | 83.68 kJ |
| 25 kcal | 104.6 kJ |
| 50 kcal | 209.2 kJ |
| 75 kcal | 313.8 kJ |
| 100 kcal | 418.4 kJ |
| 250 kcal | 1,046 kJ |
| 500 kcal | 2,092 kJ |
| 1000 kcal | 4,184 kJ |
Exact factor: 1 kilocalorie = 4.184 kilojoules. Values rounded for display.