Heat Value Converter
Convert between BTU/lb, kJ/kg, and cal/g heat value units for fuels.
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All heat value conversions use kJ/kg (kilojoules per kilogram) as the base unit.
Core conversion factors:
- 1 BTU/lb = 2.326 kJ/kg
- 1 cal/g = 4.1868 kJ/kg
- 1 BTU/lb = 0.5556 cal/g
- 1 MJ/kg = 1,000 kJ/kg
What is heat value? Heat value (also called calorific value or heating value) measures the amount of energy released when a unit mass of fuel is completely burned. It is the single most important property for comparing fuels. Higher heat value means more energy per unit of fuel, which generally translates to better efficiency and lower fuel consumption.
Common fuel heat values:
| Fuel | BTU/lb | kJ/kg | cal/g |
|---|---|---|---|
| Natural gas | 21,500 | 50,019 | 11,950 |
| Gasoline | 20,000 | 46,520 | 11,115 |
| Diesel | 18,500 | 43,031 | 10,281 |
| Coal (bituminous) | 12,500 | 29,075 | 6,946 |
| Wood (dry) | 8,500 | 19,771 | 4,724 |
| Propane | 21,660 | 50,391 | 12,039 |
| Ethanol | 11,500 | 26,749 | 6,390 |
Higher vs Lower Heating Value: Higher Heating Value (HHV) includes the energy recovered from water vapor condensation in the exhaust. Lower Heating Value (LHV) excludes that latent heat energy. The difference is typically 5-10% depending on the hydrogen content of the fuel. Most engineering calculations use LHV for gas turbines and HHV for boilers and furnaces.
Practical tip: When comparing fuel costs, always convert to the same energy unit (e.g., cost per million BTU or cost per GJ) to get a fair comparison across different fuel types.