Air Compressor CFM Calculator
Compressor size from tool air demand.
Enter your values
Enter the tool 1 demand in CFM.
Enter the tool 1 duty in %.
Enter the tool 2 demand in CFM.
Enter the tool 2 duty in %.
Enter the tool 3 demand in CFM.
Enter the tool 3 duty in %.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- 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
At a glance
| What it does | Compressor size from tool air demand. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Tool 1 demand, Tool 1 duty, Tool 2 demand, Tool 2 duty, Tool 3 demand, Tool 3 duty |
| Main output | Average demand |
| Formula | required SCFM = sum(tool CFM x duty) x 1.3 |
| Cost | Free — no sign-up, no download |
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.
Inputs explained
- Tool 1 demand(CFM)
- Enter the tool 1 demand in CFM.
- Tool 1 duty(%)
- Enter the tool 1 duty in %.
- Tool 2 demand(CFM)
- Enter the tool 2 demand in CFM.
- Tool 2 duty(%)
- Enter the tool 2 duty in %.
- Tool 3 demand(CFM)
- Enter the tool 3 demand in CFM.
- Tool 3 duty(%)
- Enter the tool 3 duty in %.
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.
What do I need to enter into the Air Compressor CFM Calculator?
Just 6 values: tool 1 demand, tool 1 duty, tool 2 demand, tool 2 duty, tool 3 demand, tool 3 duty. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Air Compressor CFM Calculator work out the answer?
Compressor sizing adds each tool's CFM demand multiplied by its duty cycle, then adds a safety margin. It applies the formula required SCFM = sum(tool CFM x duty) x 1.3 and shows the working so you can check each step by hand.
Is the Air Compressor CFM Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.