Compressor Sizing Calculator

CFM and HP from tool demand and diversity factor.

Total CFM demand

Operating pressure (psig)

Diversity factor

Safety margin

Altitude (ft above sea level)

Tab to move between fields

Required compressor CFM

46.9

Required HP

10.4

Recommended motor (HP)15

Electrical draw (kW)8.4

Compressor type2

Altitude correction factor1

How to Use This Calculator

Enter total system air demand in CFM from all connected tools and processes.
Set operating pressure in PSI and altitude correction factor for your location.
Input desired duty cycle percentage and safety factor.
Review the recommended compressor horsepower and free air delivery in CFM.
Use the motor HP and CFM ratings to select a compressor model from catalog data.

How the result changes with Total CFM demand

Total CFM demand: Sum of all tool/process CFM requirements before diversity or safety adjustments.
Operating pressure (psig): Required system operating pressure in gauge PSI.
Diversity factor: Fraction of total demand occurring simultaneously (0.75 = 75%). Lower for large facilities with many intermittent users.
Safety margin: Extra capacity for future growth and system losses. Industry standard is 20–25%.
Altitude (ft above sea level): Site elevation. Higher altitude requires more CFM due to lower air density (~3% per 1000 ft).

Required compressor CFM: Compressor output capacity needed after diversity, altitude, and safety adjustments.
Required HP: Estimated brake horsepower needed based on pressure and CFM.
Recommended motor (HP): Next standard motor size available from manufacturers.
Electrical draw (kW): Estimated full-load electrical power consumption.
Compressor type: Recommended type: 1 = Reciprocating, 2 = Rotary screw, 3 = Centrifugal.
Altitude correction factor: Multiplier applied to CFM for altitude derating.

Identify Input Parameters
4 parameters
Total CFM demand = 50, Operating pressure (psig) = 100, Diversity factor = 0.75, Safety margin = 25 = 5 input(s) provided
Calculate Required compressor CFM
Required compressor CFM = altitudeCorrectedCfm * (1 + safetyMarginPct / 100)
46.9 = 46.9
Calculate Required HP
Required HP = requiredCfm / cfmPerHp
10.4 = 10.4
Calculate Recommended motor
Recommended motor
15 = 15
Calculate Electrical draw
Electrical draw = shaftKw / motorEfficiency
8.4 = 8.4