Calculator Form
The page uses one vertical layout, while the calculator fields use a responsive grid: three columns on large screens, two on smaller screens, and one on mobile.
Plotly Graph
This chart shows how face velocity changes as coil face area changes while airflow stays fixed at the calculated or sample airflow value.
Formula Used
Face Velocity = Airflow ÷ Coil Face Area
Coil Face Area = Width × Height
Airflow = Face Velocity × Coil Face Area
Width = Required Area ÷ Height
Height = Required Area ÷ Width
How to Use This Calculator
- Select which variable you want to solve for.
- Choose whether you know coil dimensions or direct face area.
- Enter airflow, velocity, and dimensional values as needed.
- Pick the correct units for each input field.
- Press Calculate to show the result above the form.
- Review converted outputs, velocity status, and the chart.
- Use the CSV or PDF buttons to save the result.
Example Data Table
| Airflow (CFM) | Width (ft) | Height (ft) | Face Area (ft²) | Face Velocity (fpm) |
|---|---|---|---|---|
| 6000 | 4.0 | 3.0 | 12.0 | 500.0 |
| 4500 | 3.5 | 3.0 | 10.5 | 428.6 |
| 8000 | 5.0 | 3.5 | 17.5 | 457.1 |
| 3000 | 2.5 | 2.5 | 6.25 | 480.0 |
| 9500 | 6.0 | 3.5 | 21.0 | 452.4 |
Frequently Asked Questions
1. What is coil face velocity?
Coil face velocity is the air speed moving through the visible front area of a coil. It equals airflow divided by face area.
2. Why does face velocity matter?
It affects pressure drop, noise, heat transfer, moisture carryover, and equipment sizing. Excessively high velocity can reduce performance and increase operating issues.
3. What units can I use here?
You can use CFM, m³/s, m³/h, and L/s for airflow. Velocity supports m/s, fpm, and ft/s. Size inputs include metric and imperial units.
4. Can I calculate area without width and height?
Yes. Choose the area solving mode or enter a direct face area instead of dimensions. The calculator converts and uses that area automatically.
5. What is a typical coil face velocity range?
Many designs aim near 300 to 500 fpm, but exact targets depend on coil type, moisture conditions, noise limits, and project requirements.
6. Why is my velocity very high?
High velocity usually means the airflow is large for the available face area. Increase coil area or reduce airflow to lower velocity.
7. Should I use net area or gross area?
Design practice varies. Many quick checks use gross face area. Detailed manufacturer selections may use more specific effective areas and published coil data.
8. Does this replace manufacturer coil selection software?
No. It is a fast engineering calculator for screening and estimation. Final equipment selection should still follow manufacturer performance data.