BTU per hour and watts
One BTU per hour is about 0.293 watts. Air conditioners, heaters and furnaces in the US are sized in BTU/h, often written just "BTU".
The watt is the SI unit of power: one joule per second. Light bulbs, appliances, chargers and solar panels are rated in watts.
Worked example
Convert 12,000 BTU/h: 12,000 × 0.2930710702 = 3,516.852842, so 12,000 BTU per hour is 3,516.852842 watts. Likewise 10,000 BTU/h = 2,930.710702 W.
Estimating in your head
Divide by 3.4 for a quick figure; it is off by about 0.4%. For 12,000 BTU/h that gives 3,530 W, against 3,516.85 exactly.
Going the other way
To convert watts to BTU per hour, divide by 0.2930710702 (or multiply by 3.41214163313). The swap button between the boxes opens that page.
How this works
W = BTU/h × 0.2930710702
1 BTU/h = ≈ 0.2930710702 W and 1 W = 1 W, both by definition, so the factor is their ratio: 0.2930710702 (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 watts are in a BTU per hour?
1 BTU per hour = 0.2930710702 watts. 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 per hour to watts?
Multiply by 0.2930710702. For example, 10,000 BTU/h × 0.2930710702 = 2,930.710702 W.
What is 100,000 BTU/h in watts?
100,000 BTU/h = 29,307.10702 W. 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
- NIST SP 811 Appendix B.9 — Factors for units listed by kind of quantity
- Wikipedia — Horsepower
Reviewed Oct 17, 2026 · test vectors fixtures/units/power/btu-per-hour-to-watts/