SCFM Calculator — Actual to Standard Flow Rate
SCFM (standard cubic feet per minute) normalises a gas flow to reference conditions — 14.696 psia and 68 °F — so different flows can be compared on equal terms. Enter the actual flow, line pressure and temperature to get the SCFM and equivalent metric SCMH.
ACFM
Pressure unit
Temperature unit
Standard cubic feet per minute at 14.696 psia and 68 °F (20 °C)
- 1
Convert gauge to absolute pressure
100 + 14.696 = 114.696 psia - 2
Temperature in Rankine
70 F → Rankine = 529.67 °R - 3
Pressure ratio P ÷ P_std
114.696 ÷ 14.696 = 7.8046 - 4
Temperature ratio T_std ÷ T
527.67 ÷ 529.67 = 0.9962 - 5
SCFM = ACFM × P_ratio × T_ratio
100 × 7.8046 × 0.9962 = 777.51
Conas a oibríonn an t-áireamhán seo?
SCFM = ACFM × (P_actual / 14.696) × (527.67 / T_actual_R). Convert gauge pressure to absolute by adding 14.696 psi; convert °F to Rankine by adding 459.67. Higher actual pressure → more SCFM than ACFM; higher temperature → fewer SCFM than ACFM. Standard reference: 14.696 psia, 68 °F (CAGI/ISO 13443).
Foirmle
How this is calculated
A gas at higher pressure is denser — the same pipe carries more molecules per unit volume. If you report a flow in "actual" units (ACFM) you are counting volumes at whatever conditions exist at the measurement point. That number is useless for comparing equipment or sizing compressors unless everyone uses the same reference.
SCFM fixes this by correcting the actual flow to a standard reference state using the ideal-gas law. Because PV = nRT, doubling the absolute pressure at constant temperature halves the volume — so SCFM = ACFM × (P_actual / P_std) × (T_std / T_actual), where pressures are in absolute units and temperatures in absolute degrees (Rankine). Gauge pressure (psig) is converted to absolute (psia) by adding 14.696 — the standard atmospheric pressure.
The reference conditions used here are 14.696 psia (1 atm) and 68 °F (20 °C), which are the CAGI and ISO 13443 standard conditions for compressed air and natural gas. Some industries use 60 °F (NTP in North America for gas pipelines) or 0 °C (0 °C/SATP); check your equipment spec. The metric equivalent SCMH (standard cubic metres per hour) is also shown; 1 SCFM = 1.6990 SCMH. This calculator assumes ideal-gas behaviour, which is accurate for air and common gases at moderate pressures (below ~150 bar).
Ceisteanna coitianta
ACFM is the actual volume flow at operating conditions (pressure and temperature). SCFM normalises that flow to standard reference conditions (14.696 psia, 68 °F) so equipment can be compared. At pressures above atmospheric, SCFM > ACFM; at sub-atmospheric pressures, SCFM < ACFM.
The SCFM formula uses absolute pressure. Gauge pressure (psig) is measured relative to atmosphere and must have 14.696 psi added to get absolute (psia). Forgetting this step introduces an error proportional to atmospheric pressure — significant at low pressures.
Yes. The correction uses PV = nRT, which is accurate for air and most gases at pressures below ~150 bar (2175 psi). For very high pressures or near the critical point of a gas, real-gas (compressibility) corrections are needed.
Ar a dtugtar freisin
TG we-Calculate Editorial Team. (2026). SCFM Calculator — Actual to Standard Flow Rate [Online calculator]. TG we-Calculate. https://we-calculate.com/ga/calculator/scfm-calculator
TG we-Calculate Editorial Team. "SCFM Calculator — Actual to Standard Flow Rate." TG we-Calculate. 2026. https://we-calculate.com/ga/calculator/scfm-calculator.
TG we-Calculate Editorial Team, "SCFM Calculator — Actual to Standard Flow Rate," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/ga/calculator/scfm-calculator
@misc{wecalculate_scfm_calculator, title = {SCFM Calculator — Actual to Standard Flow Rate}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/ga/calculator/scfm-calculator}}, year = {2026}, note = {TG we-Calculate} }
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