Convert calories to kilojoules

Explanation

From this page you can convert calories to kilojoules (or cal to kJ) simply, by using the application above.

In case you are wondering, to convert from calories to kilojoules you need to multiply by 0.004184. This factor is calculated using the respective definitions of the two units you can find below.

Formula

1 cal=0.004184 kJ

caloriescal

dimension	energy
symbol	cal

The calorie (cal) is a unit of energy.

In this converter "calorie" refers to the thermochemical calorie.

When talking about food the word calorie almost always refers to the kilocalorie (kcal).

Definition of the calorie

One calorie is 4.184 joules.

NIST Guide to the SI, Appendix B.9

History

The calorie was first defined as the amount of energy needed to raise the temperature of one kilogram of water by one degree Celsius.

The "Thermochemical calorie" was defined by Frederick Rossini simply as 4.1833 international joules in order to avoid the difficulties associated with uncertainties about the heat capacity of water. ^[source]

In 1948 the CGPM abandonned the international ampere for the absolute ampere, ^[source] as a result, the thermochemical calorie was redefined as 4.184 joules exactly to represent the same quantity of energy as before.

Some Facts

Since the tonne of TNT is defined as 4.184 gigajoules, one calorie is the energy equivalent to the detonation of one milligram of TNT (or one nanotonne of TNT).

Calories

calorie	cal	1
kilocalorie	kcal	1000

Related Conversions

kilojouleskJ

dimension	energy
system	International system of units (SI)
symbol	kJ

The kilojoule (kJ) is a unit of energy in the International System of Units.

Definition of the kilojoule

One kilojoule is 1000 joules.

Equivalences

One kilojoule is equivalent to:

Some Facts

The estimated amount of energy the Earth receives from the Sun is 1.361 kilojoules per second and per square meters.

Prefix

kilo

10³

The prefix kilo- comes from the ancient Greek chilioi meaning thousand. The associated multiplicative factor is 1000 or 10³.

SI Energy Units

picojoule	pJ	0.000 000 000 001
nanojoule	nJ	0.000 000 001
microjoule	µJ	0.000 001
millijoule	mJ	0.001
joule	J	1
kilojoule	kJ	1000
megajoule	MJ	1 000 000
gigajoule	GJ	1 000 000 000
terajoule	TJ	1 000 000 000 000