Energy and power unit converter

Convert between the energy and power units used in energy statistics. Every factor is a defined value, listed with its source below.

Energy

Value

From

Show this value in every energy unit

The value above in every energy unit
Unit	Value
J joule	–
kJ kilojoule	–
MJ megajoule	–
GJ gigajoule	–
PJ petajoule	–
EJ exajoule	–
Wh watt-hour	–
kWh kilowatt-hour	–
MWh megawatt-hour	–
GWh gigawatt-hour	–
TWh terawatt-hour	–
Btu British thermal unit (International Table)	–
MMBtu million Btu	–
therm therm	–
quad quad (quadrillion Btu)	–
cal (IT) calorie (International Table)	–
kcal (IT) kilocalorie (International Table)	–
cal (th) calorie (thermochemical)	–
kcal (th) kilocalorie (thermochemical; food “Calorie”)	–
toe tonne of oil equivalent	–
Mtoe million tonnes of oil equivalent	–

Power

Value

From

Show this value in every power unit

The value above in every power unit
Unit	Value
W watt	–
kW kilowatt	–
MW megawatt	–
GW gigawatt	–
TW terawatt	–
hp horsepower (mechanical, 550 ft·lbf/s)	–
Btu/h Btu (International Table) per hour	–

Energy is not power

Power is a rate: how fast energy is produced or used, in watts (W, kW, MW, GW). A power plant's capacity is a power. Energy is an amount: power sustained over time, in joules or watt-hours (Wh, kWh, MWh, TWh). A year of generation is an energy.

E = P \times t \qquad 1\ \text{kWh} = 1\ \text{kW} \times 1\ \text{h} = 1{,}000\ \text{W} \times 3{,}600\ \text{s} = 3.6\ \text{MJ}

\begin{gathered}E = P \times t\\[4pt] 1\ \text{kWh} = 1\ \text{kW} \times 1\ \text{h} = 3.6\ \text{MJ}\end{gathered}

So kWh measures energy and kW measures power. The two cannot be converted into each other without a time span. Converting “kW to kWh” always needs a duration. The capacity factor calculator does that for a plant over a period.

Each conversion multiplies by the size of the source unit and divides by the size of the target unit, both expressed in the SI unit (joules for energy, watts for power):

x_{\text{to}} = x_{\text{from}} \times \frac{f_{\text{from}}}{f_{\text{to}}}

Conversion factors

Values are exact by definition unless the definition column says otherwise. Results are shown to seven significant figures.

Energy units, in joules (J)
Unit	Name	1 unit in J	Definition	Source
`J`	joule	1	SI unit of energy: 1 N·m = 1 W·s	SI
`kJ`	kilojoule	1,000	10³ J	SI
`MJ`	megajoule	1,000,000	10⁶ J	SI
`GJ`	gigajoule	1 × 10⁹	10⁹ J	SI
`PJ`	petajoule	1 × 10¹⁵	10¹⁵ J	SI
`EJ`	exajoule	1 × 10¹⁸	10¹⁸ J	SI
`Wh`	watt-hour	3,600	1 W × 3,600 s = 3,600 J	SI
`kWh`	kilowatt-hour	3,600,000	1 kW × 1 h = 3.6 × 10⁶ J	NIST
`MWh`	megawatt-hour	3.6 × 10⁹	10³ kWh = 3.6 × 10⁹ J	SI
`GWh`	gigawatt-hour	3.6 × 10¹²	10⁶ kWh = 3.6 × 10¹² J	SI
`TWh`	terawatt-hour	3.6 × 10¹⁵	10⁹ kWh = 3.6 × 10¹⁵ J (3.6 PJ)	SI
`Btu`	British thermal unit (International Table)	1,055.05585262	1,055.055 852 62 J (NIST lists 1.055 056 × 10³ J)	NIST
`MMBtu`	million Btu	1.05505585262 × 10⁹	10⁶ Btu	EIA
`therm`	therm	1.05505585262 × 10⁸	10⁵ Btu (EIA). NIST's U.S. therm, based on the 59 °F Btu, is 1.054 804 × 10⁸ J	EIA
`quad`	quad (quadrillion Btu)	1.05505585262 × 10¹⁸	10¹⁵ Btu	EIA
`cal (IT)`	calorie (International Table)	4.1868	4.1868 J	NIST
`kcal (IT)`	kilocalorie (International Table)	4,186.8	10³ cal_IT = 4,186.8 J	NIST
`cal (th)`	calorie (thermochemical)	4.184	4.184 J	NIST
`kcal (th)`	kilocalorie (thermochemical; food “Calorie”)	4,184	10³ cal_th = 4,184 J	NIST
`toe`	tonne of oil equivalent	4.1868 × 10¹⁰	10⁷ kcal_IT = 41.868 GJ (IEA/OECD convention)	IEA
`Mtoe`	million tonnes of oil equivalent	4.1868 × 10¹⁶	10⁶ toe = 41.868 PJ	IEA

Power units, in watts (W)
Unit	Name	1 unit in W	Definition	Source
`W`	watt	1	SI unit of power: 1 J/s	SI
`kW`	kilowatt	1,000	10³ W	SI
`MW`	megawatt	1,000,000	10⁶ W	SI
`GW`	gigawatt	1 × 10⁹	10⁹ W	SI
`TW`	terawatt	1 × 10¹²	10¹² W	SI
`hp`	horsepower (mechanical, 550 ft·lbf/s)	745.69987158227	745.699 871 582 27 W (NIST lists 7.456 999 × 10² W)	NIST
`Btu/h`	Btu (International Table) per hour	0.293071070172222	1,055.055 852 62 J ÷ 3,600 s ≈ 0.293 071 W (NIST: 2.930 711 × 10⁻¹ W)	NIST

Sources for the definitions

Primary energy in kWh Lab charts uses 1 EJ = 277.78 TWh (from 1 TWh = 3.6 PJ). See the methodology and the units primer.