Joules to Megaelectronvolts (J to MeV)

1 joule equals 6,241,509,074,461 megaelectronvolts (rounded).

1 joule = 6,241,509,074,461 megaelectronvolts

How to convert joules to megaelectronvolts

To convert joules to megaelectronvolts, multiply the number of joules by 6,241,509,074,461. The factor is rounded to 10 significant digits. To go the other way, multiply megaelectronvolts by 1.602176634×10⁻¹³.

megaelectronvolts = joules × 6,241,509,074,461

Example: 10 joules = 62,415,090,744,608 megaelectronvolts.

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

About these units

Joule (J)

Metric (SI)Current unit

The SI unit of energy: the work done by a force of one newton over one meter, or one watt for one second.

James Prescott Joule was born in Salford on 24 December 1818, the son of a wealthy brewer, and later ran the family brewery while treating science as a serious hobby. In June 1845 he told a British Association meeting in Cambridge about his best-known experiment: a falling weight turned a paddle wheel inside an insulated barrel of water, and the water warmed up. Mechanical work turned into heat at a fixed rate, which supported energy conservation and undermined the caloric theory of heat.

The unit came later. On 23 August 1882 Carl Wilhelm Siemens proposed at a British Association meeting that a unit of heat equal to 10 million ergs be named the joule, and in 1889 the second International Electrical Congress adopted it alongside the watt. Joule died that same year. In 1948 the CGPM added that the joule should be preferred to the calorie as the unit of heat, and it entered the SI in 1960.

For scale, one joule is about the energy needed to lift an apple of roughly 102 g by one meter. A 56 g tennis ball moving at 6 m/s carries about one joule of kinetic energy.

The joule is the reference unit for energy on this site.

Sources: Wikipedia: Joule; Wikipedia: James Prescott Joule

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

Related conversions

See all energy units.