Compressed Air CFM Demand: How to Size a Compressor Correctly
Compressed air is the most expensive utility in many plants. Sizing the compressor to real demand — not nameplate tool ratings — is the first step to an efficient system.
This guide builds CFM demand from the ground up, including the leakage allowance most plants forget.
The formula
CFM = Σ(tool CFM × utilization) × (1 + leakage). Utilization captures duty cycle; leakage adds 10–30% in real systems.
Worked example
Ten tools at 4 CFM each, used 50% of the time, with 10% leakage: 10 × 4 × 0.5 × 1.10 = 22 CFM. Size the compressor with margin above this figure.
Hunt the leaks
20–30% of generated air typically leaks away. An ultrasonic survey usually pays back in months.
Related calculators
Frequently asked questions
Typical leakage allowance?
Industrial systems usually lose 10–30% of total flow to leaks.
Should I oversize?
Add margin, but heavy oversizing wastes energy at part load — consider a VSD trim unit instead.
This guide is for educational purposes. Always verify against the relevant standard before final design.