PC Airflow & Case Pressure Calculator | Fan CFM Tool

How to Read Your Results

This tool adds up the airflow from your intake and exhaust fans so you can see what kind of case pressure your build has. Each number below tells you something different about how air moves through your case.

• Total Intake CFM: The total cubic feet of air per minute your intake fans pull in.
• Total Exhaust CFM: The total cubic feet of air per minute your exhaust fans push out.
• Net Airflow: Intake minus exhaust. A positive number means more air is coming in than going out.
• Case Pressure Ratio: Intake divided by exhaust. A ratio of 1.10 to 1.20 is a good target.
• Pressure Type: Positive, negative, or balanced, based on which side is moving more air.

What the Pressure Type Means

Positive is the result most builds should aim for. More air comes in than goes out, so dust only enters through your filtered intake fans. Negative pulls unfiltered air in through every gap, so dust builds up faster. Balanced sits in the middle and is hard to hold steady since fan output changes with load.

For the full guide on fan placement, case selection, and how to plan a quiet, cool build, read our PC airflow optimization article.