BTU and kilowatt-hours
The International Table BTU is 1,055.05585262 joules, about the energy to warm one pound of water by 1 °F. Furnaces, boilers, grills and natural gas in the US are rated in BTU.
A kilowatt-hour is 1,000 watts for one hour: exactly 3.6 million joules. Electricity bills, EV batteries and appliance energy labels use kWh.
Worked example
Convert 100,000 BTU: 100,000 × 0.0002930710702 = 29.30710702, so 100,000 BTU is 29.30710702 kilowatt-hours. Likewise 200,000 BTU = 58.61421403 kWh.
Estimating in your head
Divide by 3,400 for a quick figure; it is off by about 0.4%. For 100,000 BTU that gives 29.4 kWh, against 29.3071 exactly.
Going the other way
To convert kilowatt-hours to BTU, divide by 0.0002930710702 (or multiply by 3,412.14163313). The swap button between the boxes opens that page.
How this works
kWh = BTU × 0.0002930710702
1 BTU = 1,055.05585262 J and 1 kWh = 3,600,000 J, both by definition, so the factor is their ratio: 0.0002930710702 (rounded here; the page uses the full value). Results drop binary floating-point noise beyond 15 significant digits and display at the precision you choose (6 significant figures by default). Copy result copies the full value.
Frequently asked
How many kilowatt-hours are in a British thermal unit?
1 British thermal unit = 0.0002930710702 kilowatt-hours. The factor is exact by definition but has endless decimals, so it is shown rounded; the page uses the full value.
How do I convert BTU to kilowatt-hours?
Multiply by 0.0002930710702. For example, 200,000 BTU × 0.0002930710702 = 58.61421403 kWh.
What is 1,000,000 BTU in kilowatt-hours?
1,000,000 BTU = 293.0710702 kWh. The table next to the converter lists more common values.
Is the result rounded?
Only on screen. The page computes with the exact definitions and removes floating-point noise past 15 significant digits; pick 3 to 12 significant figures, or use Copy result for the full value.
Sources
- NIST SP 811 Appendix B.8 — Factors for units listed alphabetically
- BIPM — The International System of Units (SI Brochure), 9th edition
- Wikipedia — Calorie
Reviewed Oct 17, 2026 · test vectors fixtures/units/energy/btu-to-kwh/