Kilojoules to Kilocalories Converter

Kilojoules to Kilocalories

Convert kilojoules (kJ) to kilocalories (kcal). Both measure work and power, and the conversion comes up in nutrition, electricity, fitness work.

The Formula

`` kilocalories = kilojoules × 0.239005736138 kilojoules = kilocalories × 4.184 `

One kilojoule is 0.239006 kilocalories, and one kilocalory is 4.184 kilojoules.

Conversion Table

Kilojoules	Kilocalories
1 kJ	0.239006 kcal
2 kJ	0.478011 kcal
5 kJ	1.195 kcal
10 kJ	2.3901 kcal
25 kJ	5.9751 kcal
50 kJ	11.9503 kcal
100 kJ	23.9006 kcal
500 kJ	119.5029 kcal
1,000 kJ	239.0057 kcal

The Other Direction

Kilocalories	Kilojoules
1 kcal	4.184 kJ
2 kcal	8.368 kJ
5 kcal	20.92 kJ
10 kcal	41.84 kJ
25 kcal	104.6 kJ
50 kcal	209.2 kJ
100 kcal	418.4 kJ
500 kcal	2,092 kJ
1,000 kcal	4,184 kJ

What Each Unit Is

Kilojoules (kJ) — 1,000 joules. The metric food-energy unit outside North America.

Kilocalories (kcal) — 1,000 small calories, or 4,184 joules — the "Calorie" on a nutrition label. Capitalised as Calorie to distinguish it, a convention almost nobody follows.

A Sense of Scale

• An apple holds about 400 kJ
• Daily intake is around 8,700 kJ
• An apple is 95 kcal
• Daily intake is about 2,000 kcal
• A marathon burns roughly 2,600 kcal

Precision

The factor 0.239005736138 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.

In Code

`javascript const kilojouleToKilocalorie = (value) => value * 0.239005736138; ``

Where This Conversion Comes Up

• Nutrition
• Electricity
• Fitness
• Heating
• Fuel

How Many Decimals Do You Need?

Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 kJ with the factor truncated at each decimal place:

Decimals kept	Factor	137 kJ becomes	Error
0	0	0	100.0000%
1	0.2	27.4	16.3200%
2	0.24	32.88	0.4160%
3	0.239	32.743	0.0024%
4	0.239	32.743	0.0024%

A rule that holds for any conversion: round once, at the end. Rounding the factor and then multiplying compounds the error through every subsequent calculation, while carrying full precision and rounding the final answer does not.

The right number of significant figures is set by your input, not by the converter. If you measured kilojoules to three significant figures, the answer in kilocalories is only good to three — writing more digits claims precision the measurement never had.

Other Conversions From Kilojoules

The same value in every other unit this converter supports for energy:

From	To	Unit
1 kJ	1,000 J	Joules
1 kJ	239.006 cal	Calories
1 kJ	0.277778 Wh	Watt Hours
1 kJ	2.7778e-4 kWh	Kilowatt Hours
1 kJ	0.947817 BTU	BTU

Chaining conversions works — kilojoules to metres to feet gives the same answer as kilojoules to feet — but each step rounds, so a chain of three conversions carries three roundings. Convert directly where a direct factor exists.