Megaelectronvolts to Calories (MeV to cal)

1 megaelectronvolt equals 3.829294058×10⁻¹⁴ calories (rounded).

1 megaelectronvolt = 3.829294058×10⁻¹⁴ calories

How to convert megaelectronvolts to calories

To convert megaelectronvolts to calories, multiply the number of megaelectronvolts by 3.829294058×10⁻¹⁴. The factor is rounded to 10 significant digits. To go the other way, multiply calories by 26,114,473,967,544 (rounded).

calories = megaelectronvolts × 3.829294058×10⁻¹⁴

Example: 10 megaelectronvolts = 3.829294058×10⁻¹³ 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

Megaelectronvolt (MeV)

ScientificCurrent unit

One million electronvolts. The scale of nuclear reactions.

Nuclei trade energy in millions of electronvolts. In binding-energy tables, medium-mass nuclei hold about 8.8 MeV per nucleon, with iron-56 listed at 8.7906 MeV. Fusing deuterium with tritium releases about 17.53 MeV per reaction, while an electron and positron annihilating give 1.022 MeV. One megaelectronvolt equals 1.602176634 x 10^-13 J, so even these reactions involve only tiny amounts of energy per event.

Per atom, though, the scale is enormous. A 17.53 MeV reaction is more than a million times the 1 to 10 eV that binds atoms into molecules, which is why nuclear fuels hold so much more energy than chemical ones. The electron's rest energy is 0.511 MeV and the muon's is 105.7 MeV, so the unit also serves for particle masses. A thousand MeV make one GeV, the next step up.

1 megaelectronvolt = 1.602176634×10⁻¹³ joules (exactly).

Sources: Wikipedia: Nuclear binding energy; Wikipedia: Electronvolt

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.