Heat Value Converter

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
• 1 kWh/kg = 3,600 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:

Every row here is one number expressed five ways, converted with the factors above, so the calculator and the table cannot drift apart. Treat the BTU/lb column as the source figure and the rest as arithmetic. Note also that the sources these come from are not all on the same basis: gasoline and propane are quoted here on a higher heating value, ethanol and diesel closer to a lower one, so a difference of a few percent between this table and another one usually means HHV against LHV rather than a mistake in either.

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.