CalcPanel

Compressor CFM to HP Converter #

Quickly convert between compressor CFM (cubic feet per minute) and HP (horsepower). Supports screw, piston, and rotary vane compressors at various pressures. This quick converter uses standard efficiency factors; for detailed compressor sizing, use our full air compressor sizing calculator.

Conversion Parameters

Advanced calculator

Discharge pressure adjusts specific power and CFM-per-HP ratio.

About this calculator

This quick converter handles both CFM-to-HP and HP-to-CFM directions; for advanced compressor sizing with demand calculation and multiple compressor comparison, use the full calculator. CFM-to-HP conversion depends on compressor type, pressure, and efficiency. Typical CFM/HP ratios at 100 PSIG: screw VSD 4.5-5.0, standard screw 3.5-4.0, piston 3.0-3.5, rotary vane 3.5-4.0. Higher pressure reduces CFM/HP. Example: a 50 HP standard screw compressor at 100 PSI produces approximately 190 CFM (3.8 CFM/HP). Assumption: FAD at stated pressure, full load operation. Disclaimer: approximate values, verify with manufacturer datasheet. How to use: select direction, enter value, choose compressor type and pressure. Browse all pneumatic calculators.

Result

Converted Value
10.6 HP
CFM/HP Ratio
4.70 CFM/HP
kW Equivalent
7.9 kW
Annual Energy (@4000h, $0.12)
<,808/yr

Continue Your Calculation

After CFM/HP conversion, run full compressor sizing for total plant demand and receiver tank reserve.

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Quick Reference #

Common values and conversions for quick reference. Use these as starting points for your calculations.

ParameterImperialMetricNotes
Standard Pressure14.7 PSIA1.013 barAtmospheric at sea level
Standard Temp60F (520R)15.6C (288.7K)SCFM reference
CFM to L/s1 CFM0.4719 L/sFlow rate conversion
PSI to bar1 PSI0.06895 barPressure conversion
HP to kW1 HP0.7457 kWPower conversion

Formulas and Method #

Ideal Gas Law

P x V = n x R x T

All compressed air calculations are based on the ideal gas law, which relates pressure, volume, temperature, and amount of gas. For compressed air systems, this is used to convert between standard and actual conditions, calculate pressure drop, and determine flow rates.

Standard to Actual Conversion

ACFM = SCFM x (P_std / P_actual) x (T_actual / T_std)

Convert standard flow (SCFM) to actual flow (ACFM) at operating conditions. Actual flow is used for velocity and pressure drop calculations; standard flow is used for compressor ratings and energy calculations.

Assumptions and Limitations

This calculator provides planning-level estimates. Key assumptions: air behaves as an ideal gas (valid for pressures below 300 PSIG); standard conditions are 14.7 PSIA and 60F; no moisture or oil effects; steady-state flow. Actual results may vary based on equipment condition, altitude, temperature, and system configuration. Always verify with manufacturer datasheets and professional engineering judgment for critical applications.

Typical CFM per HP at 100 PSIG #

TypeCFM/HP50 HP ≈ CFM
Screw VSD4.5–5.0225–250
Standard screw3.5–4.0175–200
Piston3.0–3.5150–175

Frequently Asked Questions #

How many CFM per HP does an air compressor produce?

Typical CFM/HP ratios at 100 PSIG: screw VSD 4.5-5.0, standard screw 3.5-4.0, piston 3.0-3.5, rotary vane 3.5-4.0. A 5 HP compressor produces 15-25 CFM, 10 HP produces 35-50 CFM, 25 HP produces 90-125 CFM, 50 HP produces 175-250 CFM.

Does higher pressure reduce compressor CFM?

Yes. Compressor output decreases as discharge pressure increases. Typical reduction: ~2% less CFM per 10 PSI increase above 100 PSI. A compressor rated 100 CFM at 100 PSI may produce only 90 CFM at 150 PSI. Always check the manufacturer's performance curve.

What is the difference between SCFM and ACFM?

SCFM is flow at standard conditions (14.7 PSIA, 60°F). ACFM is flow at actual operating conditions. ACFM = SCFM × (P_std/P_actual) × (T_actual/T_std). At 100 PSIG, 100 SCFM ≈ 12.8 ACFM. Compressor ratings use SCFM; pipe velocity uses ACFM.