Paint Booth Airflow Calculator

• Area (ft²) = Opening width (ft) × Opening height (ft)
• CFM(face) = Area (ft²) × Face velocity (fpm)
• Volume (ft³) = Length × Width × Height
• CFM(ACH) = (Volume (ft³) × ACH) ÷ 60
• Sized CFM = Base CFM × (1 + Safety%/100)
• BHP ≈ (CFM × Static Pressure) ÷ (6356 × Fan efficiency)

1. Enter the opening width and height, then pick units.
2. Set a target face velocity for capture and overspray control.
3. Optionally fill booth dimensions and ACH for a second method.
4. Select “Use both” to size conservatively to the higher airflow.
5. Add safety factor, filter choice, and static pressure if known.
6. Press Calculate to show results, then export CSV or PDF.

Airflow basis and capture performance

Accurate airflow starts with the booth opening area and a target face velocity. Multiply area by velocity to estimate required exhaust volume. Higher velocity improves capture but raises energy use and noise. This calculator lets you test multiple targets quickly, then apply a safety factor for real losses like leaks, obstructions, and imperfect airflow distribution across the entire working opening during different spray patterns and setups.

Using air changes for enclosed booths

Air changes per hour provides a volume based perspective for enclosed booths. Compute booth volume, multiply by desired air changes, then divide by sixty to get CFM. This approach helps when openings vary or when process contamination demands a minimum turnover rate. Use both methods and size to the higher result to avoid stagnant zones and fume pockets in hot weather or with heavier coatings too.

Static pressure, filters, and fan selection

Filters, ducts, and exhaust stacks add resistance that reduces delivered airflow. Static pressure combines filter drop, duct friction, fittings, and discharge losses. Fan horsepower rises with both airflow and pressure, so small design changes can reduce operating cost. Enter estimated pressure and efficiencies to approximate brake horsepower and electrical input, then compare alternatives before purchasing equipment. Use vendor curves to validate performance at the duty point.

Margins, verification, and commissioning

Safety factors cover uncertainty from filter loading, seasonal air density changes, and measurement error. A modest margin helps maintain negative pressure and consistent capture as filters clog. For production work, verify airflow using a pitot traverse or calibrated anemometer at the face. Compare measured values to the sized airflow and update assumptions, then decide on fan speed adjustments and maintenance timing for each shift and product.

Documentation and ongoing optimization

Use the exported CSV for commissioning records and the PDF for job folders. Document opening size, velocity target, chosen method, and static pressure assumptions alongside fan model and curve. When selecting equipment, confirm the fan can deliver the sized CFM at total pressure with acceptable sound levels. Recheck results after maintenance, balancing, and filter replacement cycles to sustain performance and keep notes on filter brand changes.

What face velocity should I start with?

For general crossdraft booths, many users begin near 80–100 fpm and adjust after measuring capture and comfort. Higher values improve containment but increase noise and energy. Always follow local requirements and your coating supplier guidance.

Why does the calculator offer an ACH method?

Air changes per hour ties ventilation to booth volume, useful when openings vary or when turnover is specified in a procedure. It helps detect undersized designs that might look acceptable using opening area alone.

Should I include filter pressure drop?

Yes for planning. Filters add resistance that grows as they load. Use manufacturer data when possible, or keep a conservative allowance and verify with a manometer during commissioning to protect airflow targets.

How do I estimate static pressure for ducts?

Add losses from straight duct length, elbows, transitions, dampers, and the discharge stack. If you do not have a duct calculator, start with a rough value and refine after choosing a layout and fittings.

What does the horsepower estimate represent?

It is an approximation of brake horsepower needed at the sized airflow and pressure, adjusted by fan efficiency. Electrical input also depends on motor efficiency and controls. Use fan curves and nameplate ratings for final selection.

How can I verify results on site?

Measure face velocity at multiple points and calculate average airflow, or perform a duct traverse. Compare to the sized CFM and adjust fan speed, dampers, or filters. Record readings over time to track filter loading.