Air Compressor Sizing Calculator

Size an air compressor by calculating required CFM, HP, and tank capacity from tool demands, duty cycle, and diversity factor.

Total tool CFM demand

Duty cycle

Number of tools

Operating pressure (PSI)

Diversity / simultaneity factor

Safety margin

Electricity rate ($/kWh)

Operating hours/day

Tab to move between fields

Required CFM (adjusted)

10.08

Effective tool CFM12

Calculated HP38.95

Recommended motor HP40

Recommended tank (gal)20

Daily energy (kWh)143.23

Monthly electricity cost$378.13

Recommended pipe ID (in)0.5

How to Use This Calculator

Enter Total tool CFM demand, Duty cycle, and Number of tools.
Set Operating pressure (PSI), Diversity / simultaneity factor, and Safety margin.
Adjust Electricity rate ($/kWh), Operating hours/day as needed.
Review the Required CFM (adjusted) result.
Use Effective tool CFM and Calculated HP to inform your decision.

How the result changes with Total tool CFM demand

Total tool CFM demand: Sum of CFM ratings for all pneumatic tools.
Duty cycle: Percentage of time tools are actively running (e.g., 60% for intermittent use).
Number of tools: Total pneumatic tools connected to the system.
Operating pressure (PSI): Required line pressure at the tool.
Diversity / simultaneity factor: Percentage of tools running simultaneously (70% typical for shops).
Safety margin: Extra capacity for future expansion and losses.
Electricity rate ($/kWh): Local electricity cost per kilowatt-hour.
Operating hours/day: Hours per day the compressor runs.

Required CFM (adjusted): CFM needed after applying duty cycle, diversity, and safety margin.
Effective tool CFM: CFM demand adjusted for duty cycle only.
Calculated HP: Theoretical brake horsepower for adiabatic compression.
Recommended motor HP: Next standard motor size above calculated HP.
Recommended tank (gal): Minimum receiver tank capacity in gallons.
Daily energy (kWh): Estimated daily electricity consumption.
Monthly electricity cost: Estimated monthly electricity cost (22 working days).
Recommended pipe ID (in): Minimum main distribution pipe diameter in inches.

Identify Input Parameters
4 parameters
Total tool CFM demand = 20, Duty cycle = 60, Number of tools = 3, Operating pressure (PSI) = 90 = 8 input(s) provided
Calculate Required CFM
Required CFM = effectiveCfm * diversity * safetyMultiplier
10.08 = 10.08
Calculate Effective tool CFM
Effective tool CFM = totalToolCfm * dutyCycle
12 = 12
Calculate Calculated HP
Calculated HP = (adjustedCfm * (pow(pressureRatio, compressionExponent) - 1) * 4.36) /
38.95 = 38.95