Air Compressor Sizing Calculator
Add your pneumatic tools, set the duty cycle for each, and the calculator gives you total demand CFM, required free air delivery (FAD), and recommended compressor size with a safety margin.
Required FAD (L/min) = Σ(tool CFM × duty cycle) × 28.3 × 1.25 safety factor. Compressor kW ≈ FAD (L/min) ÷ 170 for a modern oil-flooded rotary screw at 7–8 bar. Always size receiver volume ≥ 6× compressor displacement per minute for stable pressure.
Step 1 — Add your tools
Step 2 — System parameters
These results are estimates for planning purposes. Consult a compressed air specialist for system design above 75 kW or where pressure dew point, air quality, or redundancy are critical.
How to use this calculator
- Add each pneumatic tool or consumer on site (use the + button).
- Enter the tool's CFM consumption — find this on the tool's data sheet or use the typical values in the dropdown.
- Set the duty cycle: what percentage of time is this tool running during peak demand? (e.g., a grinder used 30% of the time = 0.30)
- Set your operating pressure (7 bar is standard for most industrial tools).
- Click Calculate. The result includes a 25% safety/growth margin by default.
Common tool CFM reference
| Tool | Typical CFM | L/min equivalent |
|---|---|---|
| Angle grinder (5") | 5–8 CFM | 140–230 |
| Impact wrench (1/2") | 4–6 CFM | 110–170 |
| Impact wrench (3/4") | 7–10 CFM | 200–280 |
| Air ratchet | 3–4 CFM | 85–115 |
| Blow gun | 2–4 CFM | 55–115 |
| Needle scaler | 15–18 CFM | 425–510 |
| Pneumatic drill | 3–6 CFM | 85–170 |
| Air-powered hoist (1t) | 30–60 CFM | 850–1700 |
| Spray gun (HVLP) | 8–12 CFM | 230–340 |
| Sandblaster | 50–100 CFM | 1400–2800 |
Sizing methodology
This calculator uses the diversity method: not all tools run simultaneously at full load. The duty cycle input represents simultaneous peak usage fraction per tool.
Formula: FAD (L/min) = [Σ(CFMi × DCi)] × 28.317 × (1 + margin/100)
Compressor kW is estimated at 6.5 kW per 100 L/min FAD for a modern oil-flooded rotary screw compressor at 7 bar — typical specific power is 6.0–7.5 kW/100 L/min.
Receiver volume uses the rule: V (litres) = (demand L/min × pressure swing allowable × time) ÷ (ΔP bar). A simplified rule is V ≥ 6 × compressor displacement (L).