Joules to BTU
Convert joules to BTU. 1 BTU = 1,055.06 J. For translating SI energy data into US HVAC units.
Tips & Notes
- ✓1,055 J = 1 BTU — for rough estimates, divide joules by 1,055.
- ✓Watt-hours to BTU: 1 Wh = 3.412 BTU. Natural gas: 1 cubic foot = ~1,020 BTU = 1,075,800 J.
- ✓Combustion energy: gasoline ~47 MJ/kg = 44,552 BTU/lb.
- ✓For power: 1 watt = 1 J/s = 3.412 BTU/hr.
Common Mistakes
- ✗Confusing J with J/s (watts) — joules measure energy, watts measure power (energy per time).
- ✗Dividing by 1,000 instead of 1,055 — 1,000 J ≈ 0.948 BTU, not exactly 1 BTU.
- ✗Forgetting BTU/hr vs BTU — equipment specs use BTU/hr (power), not total BTU (energy).
- ✗Using thermochemical BTU (1,054.35 J) when IT BTU (1,055.06 J) is needed — minor but precise.
Joules to BTU Overview
What This Calculator Does
Converts joules to BTU: 1 J = 0.000947817 BTU (IT). Used for converting SI physics calculations to US thermal engineering units.
Energy Content Reference
| Energy | Joules | BTU | |--------|--------|-----| | 1 BTU | 1,055 J | 1 | | 1 kWh | 3,600,000 J | 3,412 | | 1 therm | 105,480,000 J | 100,000 | | 1 liter gasoline | ~32,000,000 J | ~30,336 |
Power Conversion
1 BTU/hr = 0.293071 watts. 1 watt = 3.41214 BTU/hr. To convert furnace output from watts to BTU/hr: multiply by 3.41214. A 30 kW furnace = 102,364 BTU/hr ≈ 100,000 BTU/hr (1 therm/hr).
Frequently Asked Questions
1,000 × 0.000947817 = 0.9478 BTU. Just under 1 BTU.
1,000,000 × 0.000947817 = 947.8 BTU. A megajoule equals nearly 1,000 BTU.
1 watt = 1 joule/second = 3.41214 BTU/hour. So a 1,000 W heater = 3,412 BTU/hr.
1 BTU = 1,055.06 joules (IT BTU). The thermochemical BTU is 1,054.35 J. The difference is negligible for practical engineering.