Air Compressor CFM Calculator

Choose required-capacity mode to calculate sustained and known peak demand from tool specifications. Choose pump-up mode to estimate interval-average local free-air delivery from receiver volume, pressure rise and elapsed time.

Required delivered capacity

Choose the rating basis for every row. An average value is not discounted again; an at-load value needs a user-entered utilization fraction to estimate sustained demand.

Tool/model preset	Rating basis	Average CFM	At-load CFM	Quantity	Utilization %	Simultaneity %	Required PSIG	Source

Measured or entered leakage allowance (CFM)

Future-capacity allowance (CFM)

Measured treatment/distribution loss (PSI)

Known sustained demand—

Known simultaneous peak—

Design sustained demand—

Minimum required rating pressure—

The output separates sustained and peak demand. It does not apply a hidden reserve factor and does not convert PSI directly to CFM.

Receiver pump-up output estimate

This mode rearranges the U.S. Department of Energy receiver-capacity equation. The result is an interval-average local free-air estimate, not an ISO 1217 acceptance-test result.

Receiver volume

Volume unit

Starting pressure (PSIG)

Ending pressure (PSIG)

Elapsed minutes

Additional seconds

Atmospheric pressure (PSIA)

Receiver volume—

Pressure rise—

Elapsed time—

Estimated local free-air delivery—

Q = V × (P_high − P_low) / (t × P_atm)

Pressure-system boundary: use values observed during normal operation. Do not exceed the receiver or compressor manufacturer's rated working pressure, bypass a safety device, or alter pressure controls to perform a calculation.

Formula sources: U.S. Department of Energy compressed-air sourcebook and NIST Handbook 44 Appendix C. Dataset version 2026-07-29.