Calories to Kilocalories Converter

Calories to Kilocalories

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

The Formula

`` kilocalories = calories × 0.001 calories = kilocalories × 1000 `

One calory is 0.001 kilocalories, and one kilocalory is 1,000 calories.

Conversion Table

Calories	Kilocalories
1 cal	0.001 kcal
2 cal	0.002 kcal
5 cal	0.005 kcal
10 cal	0.01 kcal
25 cal	0.025 kcal
50 cal	0.05 kcal
100 cal	0.1 kcal
500 cal	0.5 kcal
1,000 cal	1 kcal

The Other Direction

Kilocalories	Calories
1 kcal	1,000 cal
2 kcal	2,000 cal
5 kcal	5,000 cal
10 kcal	10,000 cal
25 kcal	25,000 cal
50 kcal	50,000 cal
100 kcal	100,000 cal
500 kcal	500,000 cal
1,000 kcal	1,000,000 cal

What Each Unit Is

Calories (cal) — the energy to raise one gram of water by one degree Celsius, or 4.184 joules — the "small" calorie. A 19th-century thermal unit, displaced by the joule in physics but retained in nutrition.

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

• A gram of sugar holds about 4,000 small calories
• An apple is 95 kcal
• Daily intake is about 2,000 kcal
• A marathon burns roughly 2,600 kcal

Precision

The factor 0.001 is exact by international agreement, not a rounded approximation. Any imprecision in a result comes from your input, not the conversion.

Watch Out For

• Food labels say "calorie" but mean kilocalorie — 1,000 of these. A 200-calorie snack is 200 kcal, or 837 kJ.

In Code

`javascript const calorieToKilocalorie = (value) => value * 0.001; ``

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 cal with the factor truncated at each decimal place:

Decimals kept	Factor	137 cal becomes	Error
0	0	0	100.0000%
1	0	0	100.0000%
2	0	0	100.0000%
3	0.001	0.137	—
4	0.001	0.137	—

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 calories to three significant figures, the answer in kilocalories is only good to three — writing more digits claims precision the measurement never had.