100 therms to kWh
100 × 105.506 MJ ÷ 3.6 = 2,930.72 kWh. Older UK gas contracts and some suppliers still quote prices per therm; divide by 29.31 to get a price per kWh.
In kilowatt-hours 2,930.72 kWh Open in the calculator
Energy unit converter
Convert energy between kWh, MJ, GJ, Btu, therms, kcal and toe, or power between kW, Btu/h, tons of refrigeration and horsepower.
You enterCalculated
Electrical
- watt-hours
- kilowatt-hoursconverting from
- megawatt-hours
SI
- kilojoules
- megajoulesthe answer
- gigajoules
Heat and gas
- kilocalories
- British thermal units
- million Btu
- therms (EC)
- therms (US)
Fuel
- tonnes of oil equivalent
Every unit at its size, in joules
The cursor is your quantity. Its number in any unit is how far it sits right of that unit’s mark: one decade for every factor of ten.
Type in the boxed unit, or press any reading to convert from that unit instead. Drag the cursor along the scale to change the quantity.
In megajoules
3.6MJ
1 kWh = 3.6 MJ.
Check the values to see a result.
- Megawatt-hours
- 0.001 MWh
- Watt-hours
- 1,000 Wh
- Gigajoules
- 0.0036 GJ
- Kilojoules
- 3,600 kJ
- British thermal units
- 3,412.14 Btu
- Million Btu
- 0.00341214 MMBtu
- Therms (EC)
- 0.0341213 therm (EC)
- Therms (US)
- 0.0341296 therm (US)
- Kilocalories
- 859.845 kcal
- Tonnes of oil equivalent
- 0.0000859845 toe
How it’s calculated
- xMJ = xkWh × 3.6=1 × 3.6=3.6 MJ
xto = xfrom × (size of the from-unit ÷ size of the to-unit)
1 kWh is 3.6 MJ.
Tip: Therms differ: the EC therm is 105.506 MJ and the US therm 105.4804 MJ. For UK and Irish gas bills the difference is under 0.03%.
How to convert energy units
Every energy unit is a fixed number of joules, so converting between them is one multiplication. 1 kWh is exactly 3.6 MJ, about 3,412 Btu and 0.03412 therms. 1 tonne of oil equivalent is 11,630 kWh.
The same holds for power: 1 kW is about 3,412 Btu per hour, and one ton of refrigeration, the US unit for chiller capacity, is 3.517 kW.
On electricity bills in the UK, Ireland and India a unit is one kWh, so 61 units is 61 kWh and a million units is 1 GWh. US natural gas is billed in therms or MMBtu: one MMBtu is 10 therms, about 293 kWh.
Any energy unit to any other
xto = xfrom × (joules per from-unit ÷ joules per to-unit)
The calculator holds each unit’s size in joules, from NIST Special Publication 811, and divides one by the other.
kWh and MJ
1 kWh = 3.6 MJ
A kilowatt for an hour is 1,000 J/s × 3,600 s = 3,600,000 J. This is exact, which is why gas bills divide megajoules by 3.6.
Btu, therms and MMBtu
1 Btu = 1055.06 J; 1 therm = 100,000 Btu
The International Table Btu is 1055.05585262 J. The EC therm is 105.506 MJ, 29.3072 kWh; the US therm is slightly smaller, 105.4804 MJ. An MMBtu, used in gas trading, is one million Btu, 293.07 kWh.
Power: kW, Btu/h, tons and horsepower
1 TR = 12,000 Btu/h = 3.517 kW
Chiller and air-conditioning capacity is often in tons of refrigeration or Btu per hour. Mechanical horsepower is 745.7 W and metric horsepower 735.5 W.
kWh to therms
therms = kWh ÷ 29.3072
Divide by 29.3072 for EC therms, or by 29.3001 for US therms. 1,000 kWh is 34.12 EC therms or 34.13 US therms. To start from a gas meter reading in cubic metres, use the gas m³ to kWh calculator first.
kWh to MMBtu
MMBtu = kWh ÷ 293.071
One MMBtu, a million Btu, is 293.071 kWh. 10,000 kWh is 34.12 MMBtu, and 100 MMBtu is 29,307 kWh.
kWh to units of electricity
1 unit = 1 kWh
The kWh register on an electricity meter counts units directly. A reading that rises from 12,480 to 12,541 over a month is 61 units, or 61 kWh, so a bill in units needs no conversion before you compare it with interval meter data.
Energy unit conversion examples
A 100-ton chiller in kW
100 × 12,000 Btu/h is 1.2 million Btu/h, which is 351.685 kW of cooling. Divide it by the electrical input to get the chiller’s COP, as the chiller COP calculator does.
In kilowatts 351.685 kW Open in the calculator
250 MWh in tonnes of oil equivalent
National energy statistics report in toe, defined as 41.868 GJ. 250 MWh is 900 GJ, or 21.4961 toe.
In tonnes of oil equivalent 21.4961 toe Open in the calculator
Energy conversion table
One of each energy unit in kWh and MJ.
| Unit | kWh | MJ |
|---|---|---|
| 1 kWh | 1 | 3.6 |
| 1 MWh | 1,000 | 3,600 |
| 1 MJ | 0.277778 | 1 |
| 1 GJ | 277.778 | 1,000 |
| 1 Btu | 0.000293071 | 0.00105506 |
| 1 MMBtu | 293.071 | 1,055.06 |
| 1 therm (EC) | 29.3072 | 105.506 |
| 1 therm (US) | 29.3001 | 105.48 |
| 1 kcal | 0.001163 | 0.0041868 |
| 1 toe | 11,630 | 41,868 |
Power conversion table
One of each power unit in kW and Btu per hour.
| Unit | kW | Btu/h |
|---|---|---|
| 1 kW | 1 | 3,412.14 |
| 1 MW | 1,000 | 3,412,142 |
| 1 Btu/h | 0.000293071 | 1 |
| 1 ton of refrigeration | 3.51685 | 12,000 |
| 1 hp | 0.7457 | 2,544.43 |
| 1 hp (metric) | 0.735499 | 2,509.63 |
Questions about energy units
How many kWh in a therm?
About 29.31 kWh. The EC therm is 29.3072 kWh and the US therm 29.3001 kWh.
How many Btu in a kWh?
About 3,412.14 Btu, using the International Table Btu.
What is the difference between kWh and kW?
kWh is energy, kW is power. This converter keeps them apart: choose Energy for kWh, MJ and therms, and Power for kW, Btu/h and tons. To go from power to energy, multiply by time with the kW to kWh calculator.
Why is a tonne of oil equivalent not exact?
It is a convention for comparing fuels, fixed at 41.868 GJ, the net calorific value of a notional crude oil. Real oils vary.
How many kWh is one unit of electricity?
One. Suppliers in the UK, Ireland and India bill electricity in units, and one unit is 1 kWh. A million units is 1,000 MWh, or 1 GWh.
How many therms are in an MMBtu?
Ten, to within 0.03%: 1 MMBtu is 9.99996 EC therms or 10.0024 US therms. Divide a gas price per MMBtu by 10 for the price per therm.
Limits of this result
- The tonne of oil equivalent is a convention (41.868 GJ, a net calorific value); other agencies have used slightly different values.
- Converting a fuel quantity to energy needs its calorific value; this converts energy units only.
- Ton of refrigeration is the US unit of 12,000 Btu per hour, not a metric tonne of anything.
Measure the energy behind the figure
Heat meters report in kWh, MWh or GJ depending on the model. A ZHM reads a wired M-Bus heat meter and passes its registers to Edge with their units.