Calorie (IT) (cal (IT))
The International Table calorie: exactly 4.1868 joules, slightly larger than the thermochemical calorie. Used in steam tables.
1 calorie (IT) = 4.1868 joules (exactly).
About the calorie (IT)
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.
Sources: Wikipedia: Calorie; NIST SP 811, Appendix B.8 (energy conversion factors); Wikipedia: Conversion of units of energy
Calorie (IT) conversion chart
1 calorie (IT) expressed in every other energy unit:
| Unit | 1 calorie (IT) |
|---|---|
| Joules | 4.1868 |
| Kilojoules | 0.0041868 |
| Watt-hours | 0.001163 |
| Kilowatt-hours | 0.000001163 |
| British Thermal Units | 0.003968320719 |
| Calories | 1.000669216 |
| Kilocalories | 0.001000669216 |
| Megajoules | 0.0000041868 |
| Gigajoules | 4.1868×10⁻⁹ |
| Megawatt-hours | 1.163×10⁻⁹ |
| Foot-pounds | 3.088025207 |
| Millijoules | 4,186.8 |
| Electronvolts | 2.613195019×10¹⁹ |
| Kiloelectronvolts | 2.613195019×10¹⁶ |
| Megaelectronvolts | 26,131,950,192,952 |
| Gigaelectronvolts | 26,131,950,193 |
| Tons Of TNT | 1.000669216×10⁻⁹ |
| Tonnes Of Oil Equivalent | 1×10⁻¹⁰ |
| Therms | 3.969268224×10⁻⁸ |
| Quads | 3.968320719×10⁻¹⁸ |
| Ergs | 41,868,000 |
| Kilogram-force Meters | 0.426934784 |
| Horsepower-hours | 0.00000155960869 |
| Liter-atmospheres | 0.04132050333 |
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