Flue Gas Mass Flow Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 27, 2026Why mass flow is the preferred basis for calculations
Volumetric flow rate changes with temperature and pressure, since gases expand and contract - mass flow rate stays constant regardless, which is why emissions reporting, energy balances, and heat loss calculations are typically done on a mass flow basis.
Worked example
For 10 m³/s of flue gas at a density of 0.7 kg/m³:
Mass Flow = 10 x 0.7 = 7.0 kg/s (25,200.0 kg/hr)
Always use the flue gas density at the actual measured conditions (temperature and pressure) where the volumetric flow rate was recorded - using a density value from different conditions will produce an incorrect mass flow result, since flue gas density itself varies significantly with temperature.