Filter Face Velocity
Use the Filter Face Velocity for hvac planning. Enter Airflow (CFM) and Filter width (in) to get a clear result, formula explanation, and practical checks.
Filter Face Velocity measurements
Enter your values, then calculate.
Result
How to calculate filter face velocity
This calculator finds air filter face velocity by dividing airflow (CFM) by the filter's face area — an important check for filter efficiency and pressure drop.
How the calculation works
Face velocity (ft/min) = CFM ÷ (Filter width in feet × Filter height in feet). Width and height are converted from inches to feet by dividing by 12.
Example
600 CFM through a 20x25 inch filter: Area = (20/12) × (25/12) ≈ 1.67 × 2.08 ≈ 3.47 sq ft; Face velocity = 600 ÷ 3.47 ≈ 173 ft/min.
Frequently asked questions
How is Result calculated?
Result = [Airflow] ÷ (([Filter width] ÷ 12) × ([Filter height] ÷ 12)).
Is the Filter Face Velocity free to use?
Yes — every calculator on Simple Calculator Tools is free, runs in your browser, and does not require an account.
Filter Face Velocity
Face velocity (ft/min) = CFM ÷ (Filter width in feet × Filter height in feet). Width and height are converted from inches to feet by dividing by 12.
Let's understand your filter face velocity result.
Calculate a result above and this guide will help you interpret it using this calculator's own formula and explanation.
Pro Tips for Filter Face Velocity
- Excessive face velocity reduces filter efficiency and increases pressure drop — many filter manufacturers specify a maximum recommended face velocity.
- Undersized filters (too small for the system's airflow) are a common cause of high face velocity and resulting filter or system issues.
Common Filter Face Velocity Mistakes to Avoid
- Using a filter sized for a smaller airflow system, resulting in excessive face velocity and reduced filtration effectiveness.
When to Use This Calculator
This calculator finds air filter face velocity by dividing airflow (CFM) by the filter's face area — an important check for filter efficiency and pressure drop.