Home
Back
Air Compressor CFM Formula:
| From: | To: |
CFM (Cubic Feet per Minute) measures the volume of air flow an air compressor can deliver. It represents the free air delivery capacity and is crucial for determining if a compressor can adequately power your air tools and equipment.
The calculator uses the CFM formula:
Where:
Explanation: This formula calculates the actual CFM output by measuring how quickly the compressor can fill its tank to the required pressure ratio.
Details: Accurate CFM calculation is essential for selecting the right compressor size, ensuring adequate air supply for tools, optimizing energy efficiency, and preventing compressor overload.
Tips: Enter tank volume in gallons, pressure ratio (typically 2-8 for most applications), and fill time in minutes. All values must be positive numbers greater than zero.
Q1: What Is Pressure Ratio?
A: Pressure ratio is the ratio of discharge pressure (PSIG + 14.7) to atmospheric pressure (14.7 PSI). For example, for 100 PSIG discharge: (100 + 14.7) / 14.7 = 7.8 ratio.
Q2: How Do I Measure Fill Time Accurately?
A: Start timing when compressor kicks on and stop when it shuts off at full pressure. Ensure tank is completely empty before starting.
Q3: What Is A Good CFM Range?
A: Small tools need 0-5 CFM, medium tools 5-10 CFM, large tools 10-20+ CFM. Always check your tool requirements and add 30% safety margin.
Q4: Why Is My Calculated CFM Lower Than Rated?
A: Actual CFM is often lower due to efficiency losses, altitude, temperature, and compressor age. This test measures real performance.
Q5: Can I Use This For All Compressor Types?
A: This method works for reciprocating, rotary screw, and centrifugal compressors. Ensure measurements are taken under standard conditions.