Convert Femtojoules to British Thermal Units
Convert Femtojoules (fJ) to British Thermal Units (BTU) instantly and accurately.
Conversion Formula
BTU = fJ × 9.478171203e-19
About Femtojoules
A femtojoule (fJ) is 10⁻¹⁵ J - the scale of gamma-ray photons, molecular motor work, and state-of-the-art digital logic. The electron rest-mass energy is 81.87 fJ; a 100 keV X-ray photon carries 16.02 fJ. A single myosin II motor protein power stroke dissipates ~5-40 fJ. ATP hydrolysis under cellular conditions yields ~80-100 fJ of free energy. Advanced 3 nm CMOS gates switch at ~0.1-1 fJ per operation. Ultrafast fiber laser oscillators produce pulses of 0.1-10 fJ before amplification. 1 fJ = 10⁻¹⁵ J = 6.242 keV.
About British Thermal Units
A British Thermal Unit (BTU) - the heat to raise 1 lb of water by 1°F - equals exactly 1,055.05585262 J. It dominates US HVAC: room air conditioners are rated in BTU/h (5,000-24,000 BTU/h = 1.5-7.0 kW); one ton of refrigeration is exactly 12,000 BTU/h. Natural gas is billed in therms (100,000 BTU) in the US. Higher heating values: natural gas ~1,020-1,050 BTU/ft³; No. 2 fuel oil ~138,700 BTU/US gal; propane ~91,500 BTU/US gal. 1 BTU = 1,055.06 J = 252.164 cal = 0.29307 Wh.
Quick Reference Table
| Femtojoules (fJ) | British Thermal Units (BTU) |
|---|---|
| 1 fJ | 9.478 × 10-19 BTU |
| 2 fJ | 1.896 × 10-18 BTU |
| 5 fJ | 4.739 × 10-18 BTU |
| 10 fJ | 9.478 × 10-18 BTU |
| 25 fJ | 2.37 × 10-17 BTU |
| 50 fJ | 4.739 × 10-17 BTU |
| 100 fJ | 9.478 × 10-17 BTU |