CFM to kg/hr Air Flow Calculator
Mass flow rate (kg/hr) is calculated from volumetric flow (CFM) using the density of air at standard conditions. At 68°F and 14.696 psia, the density of dry air is approximately...
Formula
Source: Engineering Toolbox, ASHRAE | Last reviewed: June 8, 2026
Examples
1 CFM
= 2.038 CFM
1 CFM = 2.038 kg/hr of air at standard conditions
100 CFM
= 203.8 CFM
100 CFM compressor delivers ~204 kg/hr
500 CFM
= 1019 CFM
500 CFM = 1,019 kg/hr (~1 metric ton/hr of air)
Where is this used?
HVAC outdoor air calculations: determining ventilation air mass for heating/cooling load computations.
Process air requirements: sizing air dryers and filters based on mass flow rather than volumetric flow.
Frequently Asked Questions
What density does this use for air?
Standard air density of 1.2 kg/m³ at 68°F (20°C) and sea level pressure. At other conditions, the mass flow changes. Hot air is less dense; high-altitude air is less dense. Use temperature and pressure corrections for precise work.
How does humidity affect the calculation?
Moist air is slightly less dense than dry air at the same temperature. At 90°F and 90% RH, the density drops to about 1.15 kg/m³, a ~4% reduction. For most industrial applications, dry air assumptions are adequate.
Can I use this for other gases?
No, this converter is specific to air. The factor 2.038 is derived from air density (1.2 kg/m³). For other gases, multiply by the ratio of the gas density to air density (approximately the molecular weight ratio).
Reviewed for accuracy
· Last reviewed: June 8, 2026
All calculations are for reference only. Always verify with manufacturer data and a qualified engineer for critical applications. Learn about our editorial process.