Lower Heating Value (LHV) Calculator
What Combustion Equipment Actually Sees
Lower heating value assumes water vapor formed during combustion stays as vapor and exits with the flue gas, which matches how nearly all real combustion equipment actually operates, since flue gas is normally too hot for that moisture to condense.
The Formula
LHV = HHV − (9 × H × 2.442)
Each kg of hydrogen produces 9 kg of water; 2.442 MJ/kg is water's latent heat of vaporization.
Worked Example
A fuel with an HHV of 30.86 MJ/kg and 5% hydrogen:
LHV = 30.86 − (9 × 0.05 × 2.442) = 29.76 MJ/kg
How to Use This Calculator
- Enter the fuel's HHV in MJ/kg.
- Enter the fuel's Hydrogen percentage by mass.
- Select Calculate to get LHV.
Related Calculations
Need to calculate HHV first? See the HHV Calculator, or check flue gas dew point in the Dew Point of Flue Gas Calculator.