Calories (IT) to Calories (cal (IT) to cal)

1 calorie (IT) equals 1.000669216 calories (rounded).

1 calorie (IT) = 1.000669216 calories

How to convert calories (IT) to calories

To convert calories (IT) to calories, multiply the number of calories (IT) by 1.000669216. The factor is rounded to 10 significant digits. To go the other way, multiply calories by 0.9993312315 (rounded).

calories = calories (IT) × 1.000669216

Example: 10 calories (IT) = 10.00669216 calories.

The 'calorie' on food labels is really a kilocalorie. The thermochemical calorie (4.184 J) is used here unless marked IT.

About these units

Calorie (IT) (cal (IT))

ScientificHistorical unit (no longer in standard use)

The International Table calorie: exactly 4.1868 joules, slightly larger than the thermochemical calorie. Used in steam tables.

Steam engineers needed a calorie tied to the joule rather than to the behaviour of water, and the Fifth International Conference on the Properties of Steam, held in London in July 1956, fixed one. The result, the International Table calorie, is exactly 4.1868 J, defined as 1.163 milliwatt-hours. An earlier International Steam Table calorie of 1929 was about 4.1860 J, so the 1956 choice slightly adjusted the older figure.

Compared with the thermochemical calorie of 4.184 J, the International Table version is larger by 0.0028 J, or roughly 0.07 percent. That is negligible for cooking but can matter in steam tables and engineering handbooks, where the calorie and its kilocalorie multiple of 4,186.8 J are used. NIST lists both calories as exact values and flags them separately for that reason. The figure used here for this unit is 4.1868 J. Anyone converting data should check which calorie a source assumes before comparing numbers.

1 calorie (IT) = 4.1868 joules (exactly).

Sources: Wikipedia: Calorie; NIST SP 811, Appendix B.8 (energy conversion factors); Wikipedia: Conversion of units of energy

Calorie (cal)

ScientificTraditional unit (still used in some regions)

The thermochemical calorie: exactly 4.184 joules, the energy to raise one gram of water by one degree Celsius. Not the same as the food Calorie, which is a kilocalorie.

Latin calor, meaning heat, supplied the name. Nicolas Clement used it in lectures on heat engines between 1819 and 1824, and by 1852 Pierre Favre and Jean Silbermann applied it to the small unit based on a single gram of water warmed by one degree Celsius. Because the specific heat of water varies slightly with temperature, early calories differed from one laboratory to the next. A mean value near 4.1855 J was published for the 15 degree calorie in 1950, with an uncertainty of 0.0005 J.

Chemists settled the matter by definition. The thermochemical calorie is exactly 4.184 J, which is the figure used here, and NIST lists it with that exact value. The calorie is not an SI unit and is regarded as obsolete, since the ninth General Conference on Weights and Measures in 1948 preferred the joule for heat. One thousand of these calories make a kilocalorie, the larger unit used for food, and a slightly larger calorie, the International Table version of 4.1868 J, is used in steam tables.

1 calorie = 4.184 joules (exactly).

Sources: Wikipedia: Calorie; NIST SP 811, Appendix B.8 (energy conversion factors)

Related conversions

See all energy units.