Finishing worked example

Paint Booth Airflow at 65% fan and filter efficiency: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop fan and filter efficiency to 65%, then walk the calculation through step by step. Estimate paint booth exhaust airflow from booth opening size and target face velocity.

The inputs for this scenario

  • Booth opening face area: 96 ft² (held at the documented default)
  • Target face velocity: 100 ft / min (held at the documented default)
  • Fan and filter efficiency: 65 % (the input this scenario stresses; the baseline uses 90)

Working through the calculation

  • The calculation starts from the formula this tool documents: Effective booth airflow = booth opening area × target face velocity × fan and filter efficiency.
  • Effective rate works out to 6,240 CFM at these inputs, and this is the headline figure for the scenario.
  • Base rate works out to 9,600 CFM at these inputs.
  • Loss to inefficiency works out to 3,360 CFM at these inputs.
  • Efficiency works out to 65 % at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where fan and filter efficiency sits at 90% and the headline result is 8,640 CFM, this scenario comes in 27.78% below the baseline at 6,240 CFM.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to fan and filter efficiency, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It assumes uniform velocity across the opening; real booths have dead zones and edge effects, so a compliant average CFM can still leave slow spots that trap overspray.

Results at a glance

  • Effective rate: 6,240 CFM (headline result)
  • Base rate: 9,600 CFM
  • Loss to inefficiency: 3,360 CFM
  • Efficiency: 65 %

Run it with your numbers

  • To rerun this with your own numbers, open the live Paint Booth Airflow calculator, set fan and filter efficiency to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.