Paint Booth Air Changes Calculator
Booth airflow from cross-draft velocity.
Enter your values
Enter the booth width in ft.
Enter the booth height in ft.
Enter the design velocity in FPM.
Enter the booth length in ft.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Booth airflow
- 12,600 CFM
- Cross-section
- 126 sq ft
- Air changes
- 250
- Makeup air
- 12,600 CFM tempered
- Filter face area needed
- 50.4 sq ft
Quick answer
Paint booths are sized on cross-draft velocity, typically 100 FPM for cross-flow and 50-100 FPM for downdraft.
CFM = booth cross-section x design velocity
At a glance
| What it does | Booth airflow from cross-draft velocity. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Booth width, Booth height, Design velocity, Booth length |
| Main output | Booth airflow |
| Formula | CFM = booth cross-section x design velocity |
| Cost | Free — no sign-up, no download |
How to use the Paint Booth Air Changes Calculator
- 1Measure the booth's internal width and height for the cross-section.
- 2Use 100 FPM for cross-draft booths; downdraft booths often run 50-75 FPM.
- 3Supply an equal amount of filtered, tempered makeup air.
Inputs explained
- Booth width(ft)
- Enter the booth width in ft.
- Booth height(ft)
- Enter the booth height in ft.
- Design velocity(FPM)
- Enter the design velocity in FPM.
- Booth length(ft)
- Enter the booth length in ft.
Worked example
Using the values the calculator loads with:
Inputs
- Booth width14 ft
- Booth height9 ft
- Design velocity100 FPM
- Booth length24 ft
Results
- Booth airflow12,600 CFM
- Cross-section126 sq ft
- Air changes250
- Makeup air12,600 CFM tempered
- Filter face area needed50.4 sq ft
Frequently asked questions
Why is velocity regulated?
It keeps solvent vapour below 25% of the lower explosive limit and carries overspray away from the finish.
Does more airflow improve finish?
Only up to a point — excessive velocity dries the paint before it flows out.
What do I need to enter into the Paint Booth Air Changes Calculator?
Just 4 values: booth width, booth height, design velocity, booth length. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Paint Booth Air Changes Calculator work out the answer?
Paint booths are sized on cross-draft velocity, typically 100 FPM for cross-flow and 50-100 FPM for downdraft. It applies the formula CFM = booth cross-section x design velocity and shows the working so you can check each step by hand.
Is the Paint Booth Air Changes Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.