Convert British Thermal Units to Kilojoules
Convert British Thermal Units (BTU) to Kilojoules (kJ) instantly and accurately.
Conversion Formula
kJ = BTU × 1.055055853
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 Kilojoules
A kilojoule (kJ) is exactly 1,000 J and is the standard energy unit for food and physical chemistry. EU, Australian, and NZ food labels are mandatory in kJ: recommended adult intake is ~8,400 kJ/day. Bond dissociation energies: C-H bond 413 kJ/mol; C=C double bond 614 kJ/mol; N≡N triple bond 945 kJ/mol. Specific heat of water: 4.184 kJ/(kg·K). A cyclist riding at 150 W for one hour expends 540 kJ. Charpy and Izod impact toughness tests record results in J and kJ. 1 kJ = 1,000 J = 239.0 cal = 0.94782 BTU = 0.27778 Wh.
Quick Reference Table
| British Thermal Units (BTU) | Kilojoules (kJ) |
|---|---|
| 1 BTU | 1.05506 kJ |
| 2 BTU | 2.11011 kJ |
| 5 BTU | 5.27528 kJ |
| 10 BTU | 10.5506 kJ |
| 25 BTU | 26.3764 kJ |
| 50 BTU | 52.7528 kJ |
| 100 BTU | 105.506 kJ |