Finishing worked example

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

Suppose fan and filter efficiency falls to 65%. This page works the full calculation at that level so you can see exactly which result moves and by how much. Calculate powder booth airflow from booth opening area, capture velocity, and operating efficiency.

The inputs for this scenario

  • Booth open face area: 100 ft² (held at the documented default)
  • Target capture velocity: 75 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 rate = base × factor × efficiency.
  • Effective rate works out to 4,875 CFM at these inputs, and this is the headline figure for the scenario.
  • Base rate works out to 7,500 CFM at these inputs.
  • Loss to inefficiency works out to 2,625 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 6,750 CFM, this scenario comes in 27.78% below the baseline at 4,875 CFM.
  • It multiplies open face area by target capture velocity to get base CFM, then derates by fan-and-filter efficiency to give effective airflow. When the numbers land here, the stressed input is the lever to work; the walkthrough above shows exactly how much each output recovers as it climbs back toward the baseline.

Results at a glance

  • Effective rate: 4,875 CFM (headline result)
  • Base rate: 7,500 CFM
  • Loss to inefficiency: 2,625 CFM
  • Efficiency: 65 %

Run it with your numbers

  • To rerun this with your own numbers, open the live Powder 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.