Energy Converters - Joule, Kilojoule, Watt-hour, Kilowatt-hour, BTU Converters

This energy converter provides many common conversions between energy units, joules, kilojoules, watt-hours, kilowatt-hours, BTU, etc. Select any energy unit to enter the value, click the convert button to get the value of the other energy units.

Type joules:J
Type kilojoules:kJ
Type megajoules:MJ
Type gigajoules:GJ
Type watt-hour:Wh
Type kilowatt-hour:kWh
Type megawatt-hour:MWh
Type kiloBTU:kBTUIT

Knowledge of converter

The joule (/dʒuːl/; symbol: J) is a derived unit of energy in the International System of Units. It is equal to the energy transferred to (or work done on) an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre (1 newton metre or N⋅m). It is also the energy dissipated as heat when an electric current of one ampere passes through a resistance of one ohm for one second. It is named after the English physicist James Prescott Joule (1818–1889).

The megajoule (MJ) is equal to one million (106) joules, or approximately the kinetic energy of a one megagram (tonne) vehicle moving at 161 km/h.

The gigajoule (GJ) is equal to one billion (109) joules. 6 GJ is about the chemical energy of combusting 1 barrel (159 l) of crude oil. 2 GJ is about the Planck energy unit.

The kilowatt hour (symbol kWh, kW⋅h or kW h) is a unit of energy equal to 3.6 megajoules. If the energy is being transmitted or used at a constant rate (power) over a period of time, the total energy in kilowatt hours is equal to the power in kilowatts multiplied by the time in hours. The kilowatt hour is commonly used as a billing unit for energy delivered to consumers by electric utilities.

The British thermal unit (Btu or BTU) is a traditional unit of heat; it is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. It is part of the United States customary units. Its counterpart in the metric system is the calorie, which is defined as the amount of heat required to raise the temperature of one gram of water by one degree Celsius. Heat is now known to be equivalent to energy, for which the SI unit is the joule; one BTU is about 1055 joules.

Energy unit conversion table

joulewatt hourkilowatt hourelectronvoltcalorie
1 J = 1 kg⋅m2⋅s−2 =12.77778 × 10−42.77778 × 10−76.241 × 10180.239
1 W⋅h =3.6 × 10310.0012.247 × 1022859.8
1 kW⋅h =3.6 × 1061,00012.247 × 10258.598 × 105
1 eV =1.602 × 10−194.45 × 10−234.45 × 10−2613.827 × 10−20
1 cal =4.21.163 × 10−31.163 × 10−62.613 × 10191

SI multiples for watt hour (W⋅h) table

10−3mW⋅hmilliwatt hour103kW⋅hkilowatt hour
10−6µW⋅hmicrowatt hour106MW⋅hmegawatt hour
109GW⋅hgigawatt hour
1012TW⋅hterawatt hour
1015PW⋅hpetawatt hour

One Btu is approximately:

  1. 1.054 to 1.060 kJ (kilojoules)
  2. 0.2931 W⋅h (watt hours)
  3. 252 to 253 cal (calories, or "little calories")
  4. 0.25 kcal (kilocalories, "large calories", or "food calories")
  5. 25,031 to 25,160 ft⋅pdl (foot-poundal)
  6. 778 to 782 ft⋅lbf (foot-pounds-force)
  7. 5.40395 (lbf/in2)⋅ft3