Joules to Kiloelectronvolts (J to keV)

1 joule equals 6.241509074×10¹⁵ kiloelectronvolts (rounded).

1 joule = 6.241509074×10¹⁵ kiloelectronvolts

How to convert joules to kiloelectronvolts

To convert joules to kiloelectronvolts, multiply the number of joules by 6.241509074×10¹⁵. The factor is rounded to 10 significant digits. To go the other way, multiply kiloelectronvolts by 1.602176634×10⁻¹⁶.

kiloelectronvolts = joules × 6.241509074×10¹⁵

Example: 10 joules = 6.241509074×10¹⁶ kiloelectronvolts.

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

Kiloelectronvolt (keV)

ScientificCurrent unit

1,000 electronvolts. X-ray photon energies are in this range.

X-rays are the usual home of the keV. Wilhelm Roentgen discovered them on 8 November 1895, and their photon energies span about 100 eV to 100 keV. Photons above roughly 5 to 10 keV count as hard X-rays, while lower ones are soft. Medical diagnostic tubes run at 20 to 150 kilovolts, which sets the highest photon energies of a radiograph at about 20 to 150 keV. One keV is 1.602176634 x 10^-16 J.

Fusion research uses it for temperature. A magnetic confinement plasma at about 15 keV corresponds to roughly 174 million kelvin. Compared with the electronvolt, a kiloelectronvolt is a thousand times larger, so it lies well above the 1 to 10 eV of chemical bonds, yet far below the millions of electronvolts released in nuclear reactions.

1 kiloelectronvolt = 1.602176634×10⁻¹⁶ joules (exactly).

Sources: Wikipedia: X-ray; Wikipedia: Electronvolt

Related conversions

See all energy units.