Frequently Asked Questions — Btu/lb to kJ/kg
Question: How many kJ/kg is 1 Btu/lb?
Answer: 1 Btu (IT)/lb = 2.326 kJ/kg exactly. Multiply BTU per pound by 2.326 to get kilojoules per kilogram.
Question: How do I convert Btu/lb to kJ/kg?
Answer: Multiply the value in Btu/lb by 2.326. For example, 20,000 Btu/lb × 2.326 = 46,520 kJ/kg ≈ 46.52 MJ/kg (typical for petroleum fuels).
Question: What is 1 Btu/lb in other units?
Answer: 1 Btu/lb = 2.326 kJ/kg = 0.5559 kcal/kg = 0.000646 kWh/kg. The Btu (IT) per pound is the standard unit for heating values in the US energy sector.
Question: What fuels are typically measured in Btu/lb?
Answer: In the US, coal, natural gas, and biomass are often reported in Btu/lb. Approximate values: coal ≈ 10,000–15,000 Btu/lb, natural gas ≈ 21,000 Btu/lb, gasoline ≈ 20,000 Btu/lb, diesel ≈ 19,000 Btu/lb.
Question: Why is the conversion factor 2.326 exactly?
Answer: The British Thermal Unit (IT) is defined as 1055.05585262 J, and 1 pound = 0.45359237 kg. So 1 Btu/lb = 1055.05585262 J ÷ 0.45359237 kg = 2326 J/kg = 2.326 kJ/kg exactly. This was adopted by international agreement in 1956.