SCFM to ACFM Converter
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- Serving industry since 1978
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What this calculator tells you
Nameplate ratings assume standard air. Your plant does not have standard air. Convert between standard (SCFM) and actual (ACFM) flow using your real site conditions, then size with our Air Compressor Sizing Calculator.
Your Conditions
Leave at 0 for ambient intake air.
Standard conditions per CAGI: 14.696 PSIA, 68°F, 36% relative humidity.
Results
Actual flow at your conditions:
0 ACFM
ACFM is 0% larger than SCFM at these conditions.
Site atmospheric pressure: 0 PSIA
At altitude and in summer heat, a compressor delivers less usable air than its nameplate suggests. Size with ACFM, not the brochure number. Start with our Air Compressor Sizing Calculator.
How this is calculated
- Atmospheric pressure from elevation: Pa = 14.696 x (1 - 6.8754e-6 x elevation)^5.2559 PSIA (standard atmosphere model).
- Water vapor saturation pressure: Pv_sat = 0.0886 x e^(0.0301 x T) PSIA, where T is in °F. This is an approximation, good to within a few percent over normal plant temperatures.
- ACFM = SCFM x [14.696 / (Pa + gauge PSI - RH x Pv_sat)] x [(T + 460) / 528]. Converting ACFM to SCFM divides by the same factors.
- Standard conditions per CAGI: 14.696 PSIA, 68°F, 36% relative humidity.
Estimates only. Actual results depend on your equipment and operating conditions. Call 800.825.3222 for exact sizing.
Common questions
What is the difference between SCFM and ACFM?
SCFM is airflow corrected to standard conditions, per CAGI 14.696 PSIA, 68 degrees F, and 36 percent relative humidity, so equipment can be compared on equal terms. ACFM is the actual volume of air moving at your site's real elevation, temperature, humidity, and pressure. The same mass of air takes up more volume when it is hotter, more humid, or at higher altitude, so ACFM is usually larger than SCFM.
Why does a compressor deliver less air at altitude and in hot weather?
Thinner air at altitude and expanded air in summer heat mean each cubic foot entering the compressor contains less air mass. A compressor rated at its nameplate flow under standard conditions delivers fewer standard cubic feet per minute of usable air when the intake air is hot, humid, or at elevation. Sizing with ACFM instead of the brochure number keeps the system from coming up short on the worst days.
How do I convert SCFM to ACFM?
ACFM = SCFM x (14.696 / (atmospheric pressure + gauge pressure - relative humidity x water vapor saturation pressure)) x ((temperature in F + 460) / 528). Atmospheric pressure comes from your elevation, and the vapor pressure term removes the volume taken up by water vapor. Converting the other direction divides by the same factors.
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These are estimates. An air audit gives you measurements.
A week of logged data on your actual system beats any rule of thumb. Our engineers run no-obligation compressed air audits across 14 Midwest locations.