SCFM to ACFM Calculator
To convert SCFM to ACFM, multiply by (T_actual ÷ T_std) × (P_std ÷ P_actual) using absolute values: 100 SCFM of air compressed to 100 psig at 68 °F is 12.82 ACFM.
12.81649453 ACFM
100 SCFM × 0.1281649453 = 12.81649453 ACFM
How this was calculated:
- T_ref = 293.15 K, P_ref = 101.3529322 kPa (absolute)
- T_actual = 293.15 K, P_actual = 790.8007293 kPa (absolute = gauge + 101.325 kPa atmospheric)
- Q_actual = Q_standard × (T_actual ÷ T_ref) × (P_ref ÷ P_actual), so 1 standard volume = 0.1281649453 actual volumes
| Unit | Value |
|---|---|
| cubic meter per second [m³/s] | 0.006048711824 m³/s |
| cubic meter per hour [m³/h] | 21.77536257 m³/h |
| liter per second [L/s] | 6.048711824 L/s |
| liter per minute [L/min] | 362.9227094 L/min |
| cubic centimeter per second [cm³/s] | 6048.711824 cm³/s |
| cubic centimeter per minute [cm³/min] | 362922.7094 cm³/min |
| cubic foot per minute [CFM] | 12.81649453 CFM |
| US gallon per minute [GPM] | 95.874037 GPM |
SCFM to ACFM Formula
Q_actual = Q_std × (T_actual ÷ T_std) × (P_std ÷ P_actual)
T in kelvin or °R (absolute); P absolute (gauge + atmospheric)
Q_std = Q_actual × (T_std ÷ T_actual) × (P_actual ÷ P_std)
It follows from the ideal gas law, PV = nRT. A standard flow fixes the number of molecules per minute; the actual volume they occupy scales with absolute temperature and inversely with absolute pressure.
Worked Examples
- Compressed air. 100 SCFM at 100 psig and 68 °F at sea level: P_actual = 114.7 psia, so Q = 100 × 14.7 ÷ 114.7 = 12.82 ACFM.
- Fan at altitude. 1000 SCFM at 5000 ft (barometric pressure 12.23 psia) and 68 °F: Q = 1202 ACFM; the fan must move about 120 % of the sea-level volume.
- Hot exhaust. 1000 ACFM at 300 °F and atmospheric pressure: Q_std = 1000 × (527.67 ÷ 759.67) × (14.696 ÷ 14.7) = 694.4 SCFM.
Standard Reference Conditions
| Reference | Temperature | Pressure (absolute) | Note |
|---|---|---|---|
| Standard air, 68 °F and 14.7 psia | 20 °C = 68 °F | 101.353 kPa = 14.7 psia | 68 °F, 14.7 psia; the 36 % RH of the full definition is not modelled. |
| Normal, 0 °C and 101.325 kPa | 0 °C = 32 °F | 101.325 kPa = 14.696 psia | Normal cubic metres (Nm³), also SEMI E12 for sccm and SLPM. |
| 20 °C and 100 kPa | 20 °C = 68 °F | 100 kPa = 14.504 psia | ISO 1217 standard inlet conditions: 1 bar(a), 20 °C, dry air. |
| 15 °C and 101.325 kPa | 15 °C = 59 °F | 101.325 kPa = 14.696 psia | Standard reference conditions for natural gas. |
| 60 °F and 14.696 psia | 15.556 °C = 60 °F | 101.325 kPa = 14.696 psia | 60 °F with one standard atmosphere. |
| 20 °C and 101.325 kPa | 20 °C = 68 °F | 101.325 kPa = 14.696 psia | Often called NTP in HVAC and laboratory work. |
SCFM, ACFM, ICFM and Nm³/h
- SCFM: standard cubic feet per minute, a mass-like flow referenced to fixed conditions.
- ACFM: actual cubic feet per minute at the real temperature and pressure in the line or at the fan.
- ICFM: inlet cubic feet per minute, actual flow measured at a compressor inlet (after filters).
- Nm³/h: normal cubic metres per hour, referenced to 0 °C and 101.325 kPa (DIN 1343).
- sccm / SLPM: standard flows used by mass flow controllers; see sccm to SLPM.
Frequently asked questions
What is the difference between SCFM and ACFM?
SCFM (standard cubic feet per minute) is the flow the gas would have at a fixed reference temperature and pressure, so it measures the amount of gas. ACFM (actual cubic feet per minute) is the volume the gas really occupies at its current temperature and pressure.
How do I convert SCFM to ACFM?
Multiply by (T_actual ÷ T_std) × (P_std ÷ P_actual), with absolute temperatures and pressures. For 100 SCFM compressed to 100 psig at 68 °F: 100 × (14.7 ÷ 114.7) = 12.82 ACFM.
Is ACFM always larger than SCFM?
No. Above atmospheric pressure the gas is compressed, so ACFM is smaller than SCFM (compressed-air lines). At high temperature, low pressure or high altitude ACFM is larger (fans, exhausts, mountain sites).
Which standard conditions should I use?
Use the one in the specification you are matching. Compressed-air ratings in the US usually use 68 °F and 14.7 psia (CAGI), compressor tests use ISO 1217 (20 °C, 1 bar), normal cubic metres (Nm³) use 0 °C and 101.325 kPa, and the gas industry often uses 60 °F.
How do I convert SCFM to Nm³/h?
The references differ (68 °F and 14.7 psia vs 0 °C and 101.325 kPa), so it is more than a unit conversion: 1 SCFM ≈ 1.584 Nm³/h, not 1.699 m³/h.
Does this include humidity or compressibility?
No. It assumes a dry ideal gas (compressibility Z = 1), which is accurate for air at normal pressures. For humid air or high-pressure gases, apply a water-vapour or Z-factor correction.
Sources
- ISO 1217:2009 Displacement compressors — Acceptance tests, International Organization for Standardization .
- ISO 13443:1996 Natural gas — Standard reference conditions, International Organization for Standardization .
- DIN 1343:1990 Reference conditions, normal conditions, normal volume, Deutsches Institut für Normung .
- Manual of the ICAO Standard Atmosphere (Doc 7488/3), International Civil Aviation Organization .
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology .
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
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APA
Scientific Converters. (2026, October 15). SCFM to ACFM Calculator. Retrieved October 17, 2026, from https://scientificconverters.com/calculators/scfm-to-acfm/
IEEE
Scientific Converters, "SCFM to ACFM Calculator," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/calculators/scfm-to-acfm/