BTU to kWh converter
1 BTU is 0.0002931 kWh, so 1 kWh is 3,412 BTU. Type in either box; handy for US gas prices and air conditioner ratings.
1 BTU = 0.0002931 kWh (1 kWh = 3,412 BTU)
What is a BTU?
A British thermal unit started out as the heat that warms a pound of water by one degree Fahrenheit. Today it's defined as 1,055.056 joules, which rounds to 1,055 (several slightly different BTUs exist; this is the International Table one). Divide by 3.6 million (the joules in a kWh) and one BTU comes to 0.0002931 kWh. Flip it round and 1 kWh is 3,412 BTU.
Gas in the US is often priced per MMBtu, which is a million BTU, so 293.1 kWh. Air conditioners and boilers in the US are rated in BTU per hour, and that is a power: 1 BTU/h is 0.2931 W.
On the napkin
Say US gas costs $3 per MMBtu. A million BTU is 293.1 kWh, so that's 3 ÷ 293.1 = about 1.0 cent per kWh of gas.
A 12,000 BTU/h air conditioner (the "1 ton" size) moves 12,000 × 0.2931 = 3,517 W, or 3.5 kW of heat. That's its cooling capacity, not what it draws from the socket. With a coefficient of performance of 3 (an assumption; newer units do better) it takes about 3.5 ÷ 3 = 1.2 kW of electricity, the same trick a heat pump uses.
Common values
| BTU | kWh |
|---|---|
| 1 | 0.0002931 |
| 1,000 | 0.2931 |
| 100,000 | 29.31 |
| 1,000,000 (1 MMBtu) | 293.1 |
| kWh | BTU |
|---|---|
| 1 | 3,412 |
| 10 | 34,120 |
| 100 | 341,200 |
| 1,000 | 3,412,000 |
Need another unit?
The full energy converter shows any amount in every energy and power unit at once, from joules to kilowatt-hours to cups of tea.
Want to know what a heat pump would save you?
The free spreadsheet works it out from the prices on your own bill. It comes by email, together with the unit converter as a sheet. One short email a month at most.
Send me the spreadsheetsSources: 1 BTU (International Table) = 1,055.056 J, NIST Special Publication 811, Appendix B; the converter rounds it to 1,055.06 J. 1 kWh = 3.6 MJ by definition. The $3 per MMBtu is an example, not a quoted price. Air conditioner example: a coefficient of performance of 3 is an assumption.
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