Air Compressor CFM Calculator
Compressor size from tool air demand.
Enter your values
ⓘ Live results
Results
- Average demand
- 6.1 SCFM
- With 30% margin
- 7.93 SCFM
- Peak if all run together
- 21 SCFM
- Approx motor size
- 2 HP
- Tank suggestion
- 32 gallons
Quick answer
Compressor sizing adds each tool's CFM demand multiplied by its duty cycle, then adds a safety margin.
required SCFM = sum(tool CFM x duty) x 1.3
How to use the Air Compressor CFM Calculator
- 1List each tool's CFM at its rated pressure from the manual.
- 2Estimate how much of each minute the tool actually runs.
- 3Add 30% headroom so the compressor is not running continuously.
Worked example
Using the values the calculator loads with:
Inputs
- Tool 1 demand5 CFM
- Tool 1 duty50 %
- Tool 2 demand4 CFM
- Tool 2 duty30 %
- Tool 3 demand12 CFM
- Tool 3 duty20 %
Results
- Average demand6.1 SCFM
- With 30% margin7.93 SCFM
- Peak if all run together21 SCFM
- Approx motor size2 HP
- Tank suggestion32 gallons
Frequently asked questions
Why does duty cycle matter?
A sander rated at 12 CFM used a fifth of the time only averages 2.4 CFM.
Tank size?
A bigger tank smooths peaks but does not increase sustained output.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.