Spray Gun Air Supply (CFM) Calculator

This calculator measures compressor air supply delivered to a spray gun inlet — the cubic feet per minute of compressed air a gun pulls through its hose while the trigger is open. It is not a measure of extraction volume, and it has nothing to do with air pulled away from a workspace. Enter what the gun consumes, what pressure that figure was rated at, the pressure you actually spray at, and what the compressor delivers.

Supply that falls away mid-pass is the quiet cause of half the defects painters blame on the coating: inlet pressure sags, atomisation coarsens, and a pass that started wet lands dry by the far end of the panel. The number that matters is not the compressor badge but the margin between what it delivers and what the gun draws at your working pressure.

Gun air consumption (CFM)

Printed on the gun spec sheet, usually beside a test pressure.

Pressure that figure is rated at (psi)

HVLP guns are commonly rated at 29 psi inlet, conventional guns at 40–50.

Your working inlet pressure (psi)

Read at the gun with the trigger open, not at the compressor gauge.

Compressor output (CFM at 90 psi)

Use the delivered figure on the plate, not the peak or “displacement” number.

Tank buffer (optional)

Tank (US gal)

Cut-out (psi)

Cut-in (psi)