Convert Calorie to Kilocalorie (cal → kcal)

The calorie is the chemistry energy unit, equal to 4.184 joules and used in thermochemistry calculations.

Calorie

Kilocalorie

0.001

1 cal0.001 kcalNIST · BIPM accuracy

Calorie to Kilocalorie Conversion Table

10 common values

Calorie	Kilocalorie
1 cal	0.001 kcal
10 cal	0.01 kcal
100 cal	0.1 kcal
500 cal	0.5 kcal
1,000 cal	1 kcal
5,000 cal	5 kcal
10,000 cal	10 kcal
50,000 cal	50 kcal
100,000 cal	100 kcal
500,000 cal	500 kcal

How to Convert Calorie to Kilocalorie Manually

Step by Step

Converting calories to kilocalories is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1
Take your value in calories
Start with the number of calories (cal) you want to convert.
2
Multiply by 0.001
The conversion factor from cal to kcal is 0.001. Multiply your value by this number.
3
Read the result in kilocalories
The result is your value in kilocalories (kcal).

Practical Examples

1 cal

equals

0.001 kcal

5 cal

equals

0.005 kcal

10 cal

equals

0.01 kcal

25 cal

equals

0.025 kcal

100 cal

equals

0.1 kcal

Formula

Multiply the value in calories by 0.001. For the reverse direction, multiply by 1,000.

Forwardkcal = cal × 0.001

Reversecal = kcal × 1,000

Example: 10 cal × 0.001 = 0.01 kcal

Tips

Use these in everyday conversions

1 cal = 4.184 J. 1 kcal = 4184 J.
Scientific "calorie" and nutrition "Calorie" differ by 1000×.
Prefer joules in modern scientific writing.

Common Mistakes

Avoid these

Assuming "calories" on food labels means gram calories — they are kcal.
Mixing gram calories and kilocalories in calculations.
Confusing calorie (energy) with calorimeter (apparatus).

About Calorie and Kilocalorie

What is the Calorie?

The calorie equals exactly 4.184 joules (the 'thermochemical calorie') and is the historical unit for heat in chemistry and physics. It was originally defined as the heat needed to raise 1 gram of water by 1°C (a definition that varied slightly with starting temperature, hence multiple 'calories' — 4.184 J was set as the exact thermochemical convention). The calorie is widely used in older physics and chemistry literature for reaction energies, specific heat capacities, and thermodynamic calculations. Note: this 'small calorie' (lowercase c) is 1/1000 of the food Calorie (capital C) used in nutrition. The chemistry calorie relates to the joule (4.184 J = 1 cal), the kilocalorie (1,000 cal = 1 kcal = 1 food Calorie), and the BTU (1 BTU ≈ 252 cal). Modern SI usage in scientific publications has largely replaced the calorie with the joule, but it persists in medical and chemistry contexts.

Thermodynamics and older physics texts
Chemistry energy calculations
Some engineering heat-transfer contexts

Real-world examples

Raising 1 g of water 1 °C: 1 cal. A 100 kcal snack = 100,000 small calories.

What is the Kilocalorie?

The kilocalorie equals 1,000 small calories or exactly 4.184 kilojoules and is the universal unit for measuring dietary energy in food. Confusingly, on US food labels and in popular usage, 'Calorie' (capital C) means kilocalorie — so a 200-Calorie cookie is actually 200,000 small calories, or 200 kcal. This convention dates to American chemist Wilbur Atwater's 19th-century nutrition research. Recommended daily intake is roughly 2,000 kcal for women and 2,500 kcal for men. The kilocalorie remains the everyday food-energy unit in the United States, while European labels show both kJ and kcal. Athletes track caloric burn during exercise in kcal: running burns about 100 kcal per mile. The kcal relates to the kilojoule (4.184 kJ = 1 kcal), the joule (1 kcal = 4,184 J), and the BTU (1 BTU ≈ 0.252 kcal). Marathon runners burn roughly 2,600 kcal during a 42-km race.