How to convert calories to kilocalories
To convert a measurement in calories to kilocalories, multiply the value by 0.001. The conversion factor comes from the relationship between both units and the joule.
For example, to convert 5 cal to kilocalories: 5 × 0.001 = 0.005 kcal.
What is a calorie?
A calorie (small calorie) is the energy needed to raise the temperature of one gram of water by one degree Celsius, defined as exactly 4.184 joules. The calorie originated in early-19th-century thermodynamics. The thermochemical calorie, fixed at exactly 4.184 J, is the modern standard, though it is often confused with the larger food Calorie (kilocalorie).
Common uses of calories include: Chemistry and thermodynamics; Heat-of-reaction measurements; Physics heat-transfer problems; Historical energy references.
What is a kilocalorie?
A kilocalorie equals 1,000 small calories, or exactly 4,184 joules, and is the 'Calorie' shown on food nutrition labels. The food Calorie (capital C) is actually a kilocalorie. This convention, established in nutrition science, means a 500-Calorie meal contains 500 kilocalories, or about 2,092 kilojoules.
Common uses of kilocalories include: Food energy (the dietary 'Calorie'); Metabolism and exercise burn estimates; Nutrition and diet planning; Bomb-calorimetry food testing.
Calories to kilocalories worked examples
Here are some common values converted:
1 cal = 0.001 kcal 5 cal = 0.005 kcal 10 cal = 0.01 kcal 50 cal = 0.05 kcal 100 cal = 0.1 kcal
Frequently asked questions
How many kilocalories are in one calorie?
One calorie (cal) equals 0.001 kilocalories (kcal). Multiply any value in calories by 0.001 to convert to kilocalories.
How do I convert calories to kilocalories?
Multiply the value in calories by 0.001. For example, 5 cal × 0.001 = 0.005 kcal.
How do I convert kilocalories to calories?
Multiply the value in kilocalories by 1,000, or divide by 0.001. Use the swap button on the converter above to reverse the direction.
Is the calorie to kilocalorie conversion exact?
The thermochemical calorie is defined as exactly 4.184 J and the BTU as 1055.056 J. Conversions between SI energy units are exact.
What is the formula for calories to kilocalories?
The formula is: kcal = cal × 0.001. This comes from the definition of both units relative to the joule.