Layout your compressed air station easily and quickly.
AeroSwap: Flow Unit Conversion Tool
Convert with confidence. Plan with precision.
Product line Class 0 oil-free centrifugal compressors for your plant air and utility air solutions
Inlet conditions
Flow demand
Recommended arrangement lowest machine count that covers the demand within each frame's published capacity
Compressor room list edit to customize your compressor room with multiple compressor frames, including an addition to an existing site
Machine
Qty
Frame size
Flow per machine (optional)
Flow
Planned flow —
Demand —
Remaining —
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Frame capacity reference
Frame
Minimum
Maximum
Published motor range (kW)
Confused about pseudo-mass flow versus volumetric flow? Struggling to convert between imperial and metric units?
AeroSwap simplifies compressor flow rate conversions, providing fast, precise results across any units and operating conditions, all in one place. By factoring in gas type, operating parameters, and system losses, AeroSwap delivers clear, consistent data you can trust for accurate system design and equipment evaluations.
Step 1: Inlet conditions
Delivered flow accounts for leakage through seals and drains. The default reflects general industrial practice; enter the figure for your seal technology if you know it.
Step 2: Convert from
Step 3: Convert to
—
Dry flow counts only the dry gas. Wet flow includes the water vapour carried in the gas stream.
The same compressor can be described by very different numbers. Enter a flow below as the baseline. Each row shows that same machine stated another way, using the inlet conditions from Step 1, and how far the number moves from the baseline. A higher number in this table does not mean more useful air.
Stated as
Value
Unit
Change from baseline
Why it differs
Baseline
SCFM, dry (delivered) at 14.7 PSI (A), 60°F, 0% RH
SCFM
baseline
The recommended basis: dry gas actually delivered to your process, at API 672 reference conditions.
Wet or dry basis
SCFM, wet (delivered), same reference
SCFM
Counts the water vapour in the gas. Intercoolers and the dryer remove that water before the air reaches your process.
Reference condition definition
SCFM, dry (delivered) at 14.5 PSI (A), 68°F, 0% RH
SCFM
ISO 1217 and CAGI Option 2 reference. Same air, stated at a warmer, lower-pressure standard cubic foot.
SCFM, dry (delivered) at 14.7 PSI (A), 68°F, 36% RH
SCFM
CAGI Option 1 reference. A warmer standard cubic foot that also contains water vapour.
SCFM, dry (delivered) at 14.7 PSI (A), 70°F, 0% RH
SCFM
A warmer reference temperature, so each standard cubic foot holds less air.
Flow type
ICFM, inlet volume
ICFM
Volume entering the compressor at your inlet conditions, before leakage. It rises on hot, humid days although the machine delivers no more air.
FAD, delivered volume
cfm
Delivered volume at your inlet conditions. Comparable between suppliers only when both use identical inlet conditions.
Mass flow at the inlet, including moisture
lb/min
Shown for reference. A different unit, so no percentage applies.
Losses left out
SCFM, dry, calculated without the inlet air filter pressure drop Often overlooked
SCFM
Assumes the inlet air filter causes no pressure loss, overstating how much air the compressor takes in.
SCFM, dry, with leakage ignored
SCFM
Presents inlet flow as delivered flow, ignoring the loss through seals and drains.
Baseline
Nm³/min, dry (delivered) at 1.013 bar (A), 0°C, 0% RH
Nm³/min
baseline
The recommended basis in metric units: dry gas actually delivered to your process, at 1.013 bar (A), 0°C.
Wet or dry basis
Nm³/min, wet (delivered), same reference
Nm³/min
Counts the water vapour in the gas. Intercoolers and the dryer remove that water before the air reaches your process.
Reference condition definition
Nm³/min, dry (delivered) at 1 bar (A), 20°C, 0% RH
Nm³/min
ISO 1217 and CAGI Option 2 reference, common on screw compressor data sheets.
Nm³/min, dry (delivered) at 1.01353 bar (A), 20°C, 36% RH
Nm³/min
CAGI Option 1 reference. A warmer normal cubic meter that also contains water vapour.
Nm³/min, dry (delivered) at 1.013 bar (A), 15°C, 0% RH
Nm³/min
"Normal" defined at 15°C instead of 0°C.
Nm³/min, dry (delivered) at 1.013 bar (A), 20°C, 0% RH
Nm³/min
"Normal" defined at 20°C instead of 0°C.
Flow type
m³/min, inlet volume
m³/min
Volume entering the compressor at your inlet conditions, before leakage. It rises on hot, humid days although the machine delivers no more air.
FAD, delivered volume
m³/min
Delivered volume at your inlet conditions. Comparable between suppliers only when both use identical inlet conditions.
Mass flow at the inlet, including moisture
kg/min
Shown for reference. A different unit, so no percentage applies.
Losses left out
Nm³/min, dry, calculated without the inlet air filter pressure drop Often overlooked
Nm³/min
Assumes the inlet air filter causes no pressure loss, overstating how much air the compressor takes in.
Nm³/min, dry, with leakage ignored
Nm³/min
Presents inlet flow as delivered flow, ignoring the loss through seals and drains.
The recommended basis for comparing compressors
Compare compressors on SCFM, dry, delivered (or Nm³/min, dry, delivered), stated at the same reference condition for every supplier, with API 672 conditions (14.7 PSI (A), 60°F, 0% RH) as the recommended standard.
Dry, because water vapour is removed by the intercoolers and the dryer and never reaches your process. Delivered, because leakage through seals and drains is air you pay to compress but cannot use. The same reference condition, because changing the definition of a standard cubic foot changes the number without changing the machine.
Flow units explained
Flow can be expressed in three ways. Volume flow is the space the gas occupies, which changes with pressure, temperature and humidity. Mass flow is the quantity of gas itself, unaffected by those conditions. Pseudo-mass flow is a volume converted to an agreed reference condition, so that it behaves like a mass flow; change the reference condition and the number changes with it.
ICFM: inlet cubic feet per minute
The volume of gas entering the compressor, after the inlet filter, at the actual inlet pressure, temperature and humidity. ICFM has meaning only together with the inlet conditions it was calculated at.
ACFM: actual cubic feet per minute
The actual volume at a stated point in the system, at the pressure and temperature at that point. The term is often used loosely for either inlet or delivered volume, so always ask which point and which conditions are meant.
FAD: free air delivery
The volume actually delivered, after leakage, expressed at the compressor inlet conditions. FAD from two suppliers is comparable only when both used identical inlet conditions.
m³/min: cubic meters per minute
The metric unit of volume flow. On its own it does not say whether the flow is measured at the inlet or delivered, so confirm which.
SCFM: standard cubic feet per minute
Delivered flow converted to a reference condition of pressure, temperature and humidity, on a wet or dry basis. Both the basis and the reference condition must be stated for an SCFM figure to be meaningful.
Nm³/min or Nm³/hr: normal cubic meters
The metric counterpart of SCFM. "Normal" conditions vary between 0°C, 15°C and 20°C, and between 1.013 bar and 1 bar, so the reference must be stated.
Reference conditions
Each of these is a recognized standard, which is why every SCFM or Nm³ figure must state its reference condition.
Standard
Reference condition
Where you will see it
API 672 (5th edition, 3.1.47)
14.7 PSI (A), 60°F, 0% RH
Recommended standard for comparing compressors
ISO 1217 (4th edition, Annex F)
1 bar (A), 20°C, 0% RH (14.5 PSI (A), 68°F)
Screw and other displacement compressor data sheets
CAGI BL 300-2022 (4.4.16, Option 2)
14.5 PSI (A), 68°F, 0% RH
Same conditions as ISO 1217
CAGI BL 300-2022 (4.4.16, Option 1)
14.7 PSI (A), 68°F, 36% RH
Compressed air data stated with humidity in the reference
DIN 1343
1.01325 bar (A), 0°C, 0% RH
The most common meaning of "normal" in Nm³
ISO 13443
1.01325 bar (A), 15°C, 0% RH
Natural gas and fuel gas measurement
NIST normal temperature and pressure
1.01325 bar (A), 20°C
Laboratory and US government references
Realistic inlet conditions: dew point
The dew point is the temperature at which air becomes saturated and its moisture starts to condense. It measures how much water the air actually holds. Temperature and relative humidity together set the dew point: the same moisture gives a high relative humidity on a cool morning and a low one on a hot afternoon.
Compressor specifications sometimes combine the highest expected inlet temperature with 100% relative humidity. In nature these do not occur together: 100% humidity is reached only after the air has cooled well below its daily maximum. API 672 (5th edition, 6.1.2.2) notes that dew points above 92°F (33°C) seldom occur anywhere. Sizing a compressor for such conditions assumes far more moisture than the site will ever see, leading to oversized impellers, larger drivers, more cooling capacity and a higher price, with no gain in reliability. Specify a realistic relative humidity at the rated temperature, or a dew point that reflects the site.
The table shows the dew point for each combination of temperature and relative humidity. Yellow and orange cells are hot and humid but realistic: sites in regions such as India and Southeast Asia regularly see them in summer, and sizing a centrifugal compressor for them ensures it delivers its flow on the hottest days. Red cells reach or exceed 92°F (33°C), conditions that rarely if ever occur.
