Free Air Compressor Pump-Up Time & CFM Tester

Test and calculate true Free Air Delivered (FAD CFM and L/min) by timing tank pressure rise from cut-in to cut-out.

⏲️ Tank & Pump-Up Test Data

Tank Receiver Volume Gallons (US)

Or Volume in Liters Metric liters

Start Pressure (PSI) Cut-in pressure (or 0 for empty)

Stop Pressure (PSI) Cut-out pressure

Timed Seconds Stopwatch time to fill

Rated Motor HP Nameplate horsepower

📊 Measured Compressor Performance

True Free Air Delivered 0.00 CFM 0.0 L/min

Pump Delivery Efficiency 0.0 CFM/HP Industrial standard: ~3.8 to 4.2

Total Free Air Pumped 0.0 SCF Across 45 PSI rise

Empty Tank 0-135 PSI Time 0m 0s Estimated full cycle

Pump Health Diagnosis: Excellent Pump Health

Test Formula: CFM = (V_cuft × ΔP × 60) / (P_atm × Sec)

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Frequently Asked Questions

Why should I test between cut-in and cut-out rather than from zero PSI?

Testing between your typical operating pressure range (such as 90 to 135 PSI) reflects the real working backpressure the compressor encounters in your shop. Testing from 0 to 50 PSI artificially inflates CFM because the pump encounters almost no resistance against atmospheric air.

How many gallons are in a cubic foot?

There are exactly 7.48052 US gallons in one cubic foot (1 cu ft ≈ 7.48 gal).

What does Free Air Delivered (FAD) mean?

Free Air Delivered is the actual volume of air drawn in at ambient atmospheric pressure (14.7 PSI and 68°F) and successfully discharged into the storage receiver tank.

Can a dirty air filter lower compressor pump CFM?

Yes. A clogged intake air filter starves the compressor cylinders of atmospheric air, drastically lowering volumetric efficiency by up to 25% and causing the pump to run excessively hot.