High and Low Heat Values

Tool for calculating and comparing gross (high) and net (low) heating values of fuels. Includes conversion between common heating value units (Btu/lb, J/kg, kcal/kg).

Heating Value TypeDescriptionUnitValue
Gross (High) Heating ValueHeat produced when all combustion products are cooled to initial temperature and water vapor is condensedBtu/lb
Gross (High) Heating ValueHeat produced when all combustion products are cooled to initial temperature and water vapor is condensedJ/kg
Gross (High) Heating ValueHeat produced when all combustion products are cooled to initial temperature and water vapor is condensedkcal/kg
Net (Lower) Heating ValueGross heating value minus latent heat of vaporization of water vapor formed by combustionBtu/lb
Net (Lower) Heating ValueGross heating value minus latent heat of vaporization of water vapor formed by combustionJ/kg
Net (Lower) Heating ValueGross heating value minus latent heat of vaporization of water vapor formed by combustionkcal/kg

Conversion Factors

  • 1 Btu/lb = 2326.1 J/kg = 0.55556 kcal/kg
  • 1 J/kg = 0.00043 Btu/lb = 2.39×10⁻⁴ kcal/kg
  • 1 kcal/kg = 1.80 Btu/lb = 4187 J/kg

Definitions

Gross (High) Heating Value: The amount of heat produced by complete combustion of a unit quantity of fuel when all combustion products are cooled to the initial temperature and water vapor is condensed.

Net (Lower) Heating Value: Obtained by subtracting the latent heat of vaporization of the water vapor formed during combustion from the gross heating value.