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Calculation Machine

Spray Booth CFM Calculator

Booth airflow from cross-draft face velocity.

Reviewed by the Calculation Machine team · How we check our maths

Your values

ⓘ Live results

Results
Extraction airflow
12,600 CFM
Open face area
126 sq ft
Make-up air needed
11,970 CFM
Heating load at 60 °F rise
816,480 BTU/h
Filter area at 250 FPM
50.4 sq ft

Quick answer

Spray booth airflow equals the booth's open face area multiplied by the required face velocity, usually 100 FPM.

The formula

CFM = booth face area x face velocity

Worked example

Worked example

Using the values the calculator loads with.

Inputs

  • Booth width14 ft
  • Booth height9 ft
  • Face velocity100 FPM

Result

  • Extraction airflow12,600 CFM
  • Open face area126 sq ft
  • Make-up air needed11,970 CFM
  • Heating load at 60 °F rise816,480 BTU/h
  • Filter area at 250 FPM50.4 sq ft

How to use the Spray Booth CFM Calculator

  1. 1Measure the booth's open face width and height.
  2. 2Use the face velocity your local code requires — 100 FPM is common for cross-draft booths.
  3. 3Provide filtered make-up air close to the extraction rate.

Frequently asked questions

What if velocity is too low?

Overspray escapes the booth and finish quality drops; too high and you get dry spray and wasted paint.

Do filters change the fan size?

Filters raise static pressure, so pick a fan that hits the CFM at the booth's actual resistance, not free air.

About this calculator