Face Velocity Calculator

Ever wondered how fast air moves across a filter, coil, or duct? That’s where face velocity comes in. Our Face Velocity Calculator helps you find the airflow speed with just a few clicks. You’ll get clear results, step-by-step, without doing complex math.

What is Face Velocity?

Face velocity is the speed of air passing through a given area. Think of it like water flowing through a hose. The flow depends on how much air is moving and how wide the opening is.

The simple formula is:

V = Q ÷ A

Where:

• V = face velocity
• Q = airflow (volume per second)
• A = area (surface in square units)

If you know the airflow in CFM and the face area in square feet, the calculator instantly gives you velocity in feet per minute (fpm).

What is the Formula for Face Velocity?

The formula stays the same in all cases:

Face Velocity (V) = Airflow (Q) ÷ Area (A)

Example:

• Flow rate = 2000 CFM
• Area = 20 ft²
• V = 2000 ÷ 20 = 100 fpm

That means air moves at 100 feet per minute across the surface.

How to Measure Face Velocity?

You can measure face velocity in two ways.

First, you can use an anemometer, a handheld tool that checks airflow speed directly. Second, you can calculate it using airflow data and face area. That’s exactly what our calculator does for you.

How to Calculate CFM from Face Velocity?

Sometimes, you’ll know the face velocity but want the airflow. In that case, flip the formula:

Q = V × A

Example:

• V = 500 fpm
• A = 10 ft²
• Q = 500 × 10 = 5000 CFM

So, the system moves 5000 cubic feet of air per minute.

How to Calculate Coil Face Velocity?

Coil face velocity is the airflow across a cooling or heating coil. Designers use this to check efficiency and prevent water carryover.

Formula is the same:

Coil Face Velocity = Airflow ÷ Coil Face Area

Example:

• Airflow = 1200 CFM
• Coil face area = 4 ft²
• Coil face velocity = 1200 ÷ 4 = 300 fpm

How to Use Our Face Velocity Calculator

1. Enter airflow (CFM, L/s, or m³/s).
2. Enter face area (ft², m², or cm²).
3. Pick your velocity unit (fpm, m/s, fps).
4. Hit calculate.

You’ll see step-by-step results with clear conversions.

Final Verdict

The Face Velocity Calculator makes airflow math simple. Whether you’re an HVAC engineer, a student, or a DIY enthusiast, this tool saves time and avoids mistakes. It’s quick, clear, and accurate.

FAQs

What is face velocity in HVAC?

It’s the speed of air through a filter, coil, or vent face.

Why is face velocity important?

It affects energy use, comfort, and equipment life.

What’s a good coil face velocity?

Many coils run best between 400–500 fpm.

Can I convert face velocity to CFM?

Yes. Just multiply velocity by area.