Convert British Thermal Units to Attojoules
Convert British Thermal Units (BTU) to Attojoules (aJ) instantly and accurately.
Conversion Formula
aJ = BTU × 1.055055853e+21
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.
About Attojoules
An attojoule (aJ) is 10⁻¹⁸ J - the scale of individual X-ray photons and superconducting qubit circuits. A 1 keV X-ray photon carries 160 aJ; a visible green photon (~550 nm) carries ~0.36 aJ. Josephson junction energies in superconducting qubits are set in tens to hundreds of aJ to achieve quantum coherence at millikelvin temperatures. XRISM's cryogenic TES X-ray spectrometer resolves individual photon energies at the hundreds-of-aJ level with ~7 eV FWHM resolution. 1 aJ = 10⁻¹⁸ J = 6.242 eV.
Quick Reference Table
| British Thermal Units (BTU) | Attojoules (aJ) |
|---|---|
| 1 BTU | 1.055 × 1021 aJ |
| 2 BTU | 2.11 × 1021 aJ |
| 5 BTU | 5.275 × 1021 aJ |
| 10 BTU | 1.055 × 1022 aJ |
| 25 BTU | 2.638 × 1022 aJ |
| 50 BTU | 5.275 × 1022 aJ |
| 100 BTU | 1.055 × 1023 aJ |