# Hartree energy to all other Energy conversions

## Hartree energy

The Hartree energy is a physical constant equal to twice the binding energy of the electron in the ground state (the lowest-energy state) of the hydrogen atom . When a hydrogen atom is in this state, an amount of energy equal to 0.5 Hartree is necessary to free the electron and thereby cause the atom to become an ion . The value of the Hartree energy is approximately 4.36 x 10 -18 joule (J), or 27.2 electronvolts (eV). The constant gets its name from the 20th-century physicist Douglas Hartree. It is sometimes used as an energy unit in theoretical physics.

### Check your output in all other similar units

Standard Units
Joule {{joule}}
Gigajoule {{gigajoule}}
Megajoule {{megajoule}}
Kilojoule {{kilojoule}}
Millijoule {{millijoule}}
Microjoule {{microjoule}}
Nanojoule {{nanojoule}}
Attojoule {{attojoule}}
Megaelectron-volt {{megaelectronvolt}}
Kiloelectron-volt {{kiloelectronvolt}}
Electron-volt {{electronvolt}}
Erg {{erg}}
Other Units
Gigawatt-hour {{gigawatthour}}
Megawatt-hour {{megawatthour}}
Kilowatt-hour {{kilowatthour}}
Kilowatt-second {{kilowattsec}}
Watt-hour {{watthour}}
Watt-second {{wattsec}}
Newton meter {{newtonmeter}}
Horsepower hour {{horsepowerhour}}
Horsepower (metric) hour {{horsepowermetrichour}}
Kilocalorie (IT) {{kilocalorieit}}
Kilocalorie (th) {{kilocalorieth}}
Calorie (it) {{calorieit}}
Calorie (th) {{calorieth}}
Calorie (Nutritional) {{calorie}}
Btu (IT) {{btuit}}
Btu (th) {{btuth}}
Mega Btu (IT) {{megabtuit}}
Ton-hour (refrigeration) {{tonhour}}
Fuel oil equivalent {{fueloilequivalent}}
Gigaton {{gigaton}}
Megaton {{megaton}}
Kiloton {{kiloton}}
Ton {{ton}}
Dyne centimeter {{dyne}}
Gram-force meter {{gramforcemeter}}
Gram-force centimeter {{gramforcecentimeter}}
Kilogram-force centimeter {{kilogramforcecentimeter}}
Kilogram-force meter {{kilogramforcemeter}}
Kilopond meter {{kilopondmeter}}
Pound-force foot {{poundforcefoot}}
Pound-force inch {{poundforceinch}}
Ound-force inch {{oundforceinch}}
Foot-pound {{footpound}}
Inch-pound {{inchpound}}
Inch-ound {{inchound}}
Poundal foot {{poundalfoot}}
Therm {{therm}}
Therm (EC) {{thermec}}
Therm (US) {{thermus}}
Rydberg constant {{rydberg}}