Compressed Air Pressure Drop Calculator #

Quickly calculate pressure drop in compressed air piping. Enter pipe size, length, flow rate, and inlet pressure to get pressure drop in PSI or bar. This quick calculator uses the Darcy-Weisbach equation for compressed air; for full pipe sizing with velocity and material selection, use our pipe sizing calculator.

Quick Calculator: Pipe & Flow Parameters

Units

Flow Rate (SCFM)

Inlet Pressure (PSIG)

Air Temperature (°F)

Actual Internal Diameter (in)Use the selected product's documented bore, not nominal trade size

Pipe Length (ft)

Advanced calculator assumptions

Use project or manufacturer hydraulic data.

Additional Fitting Equivalent Length (ft)

Absolute Roughness (in)

For advanced pipe sizing with velocity and material selection, use the full calculator.

About this calculator

Uses Darcy-Weisbach with Reynolds-dependent friction factor, entered actual ID and absolute roughness. Standard flow is converted to actual flow at the entered inlet pressure and temperature. Fitting loss is represented only by the entered additional equivalent length. The calculation uses inlet density throughout the segment; use a compressible network model when loss is not small relative to inlet absolute pressure. Worked example: the default 100 SCFM, 100 PSIG, 70°F, 1.029 in ID, 100 ft case gives about 1.738 PSI loss and 37.7 ft/s velocity. This is a planning estimate, not material or product selection. For minimum ID screening see the pipe sizing calculator, or browse all pneumatic calculators.

Results

Pressure Drop

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Outlet Gauge Pressure

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Air Velocity

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Absolute Pressure Loss

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Continue Your Calculation

After pipe pressure drop, size the compressor for total CFM demand or select cylinder bore for actuator force.

Compressed Air Pipe Sizing Calculator →

Quick Reference #

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

Parameter	Imperial	Metric	Notes
Standard Pressure	14.7 PSIA	1.013 bar	Atmospheric at sea level
Standard Temp	60F (520R)	15.6C (288.7K)	SCFM reference
CFM to L/s	1 CFM	0.4719 L/s	Flow rate conversion
PSI to bar	1 PSI	0.06895 bar	Pressure conversion
HP to kW	1 HP	0.7457 kW	Power 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 a steady-state planning estimate using ideal-gas properties and inlet density throughout the segment. Its standard reference is 1 atm and 60°F. It does not model moisture, oil, heat transfer, elevation, dynamic demand, controls, or a pressure-dependent density profile. Use an appropriate compressible network method when the calculated loss is not small relative to inlet absolute pressure.

Pressure Budget Check #

No single allowable loss applies to every plant or segment. Assign a project pressure budget from the minimum required point-of-use pressure and the available supply pressure. Include pipes, fittings, dryers, filters, separators, valves, regulators, hoses, and transient demand. Compare clean and end-of-service component losses using current manufacturer curves.

Frequently Asked Questions #

How do you calculate compressed air pressure drop?

Convert standard flow to actual flow at inlet pressure and temperature, calculate velocity from actual internal diameter, derive Reynolds number and Darcy friction factor from roughness, then apply ΔP = f(L/D)(ρV²/2). This screen uses inlet density.

What is acceptable pressure drop in compressed air systems?

Acceptable loss comes from the project pressure budget and minimum point-of-use requirement. Account for every pipe and component, clean and dirty filter states, peak coincident demand, and transients rather than applying a universal PSI value.

Does pipe material affect pressure drop?

Material can affect roughness and available bore, but neither is determined by a material name alone. Use the selected product’s actual internal diameter and a defensible design roughness; also verify pressure, temperature, joint, and air-service ratings separately.