Wind Pressure on Vent Calculator
Wind-driven pressure and natural ventilation flow.
Enter your values
Enter the wind speed in mph.
Enter the pressure coefficient you are working with.
Enter the opening area in sq 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.
- Wind pressure
- 0.221 psf
- In inches wc
- 0.0425
- In Pa
- 10.59
- Estimated airflow
- 2,218 CFM
- Effectiveness factor
- 0.35 (oblique wind)
Quick answer
Wind pressure grows with the square of wind speed and is modified by a surface pressure coefficient.
P = 0.00256 x V² x Cp (psf, mph)
At a glance
| What it does | Wind-driven pressure and natural ventilation flow. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Wind speed, Pressure coefficient, Opening area |
| Main output | Wind pressure |
| Formula | P = 0.00256 x V² x Cp (psf, mph) |
| Cost | Free — no sign-up, no download |
How to use the Wind Pressure on Vent Calculator
- 1Enter the design wind speed at the building.
- 2Use +0.6 to +0.8 for windward faces and -0.3 to -0.6 for leeward.
- 3Cross ventilation needs openings on both faces to realise the flow.
Inputs explained
- Wind speed(mph)
- Enter the wind speed in mph.
- Pressure coefficient
- Enter the pressure coefficient you are working with.
- Opening area(sq ft)
- Enter the opening area in sq ft.
Worked example
Using the values the calculator loads with:
Inputs
- Wind speed12 mph
- Pressure coefficient0.6
- Opening area6 sq ft
Results
- Wind pressure0.221 psf
- In inches wc0.0425
- In Pa10.59
- Estimated airflow2,218 CFM
- Effectiveness factor0.35 (oblique wind)
Frequently asked questions
Why 0.35 not 0.55?
0.55 applies when wind is perpendicular; 0.35 covers typical oblique angles over a year.
Wind or stack effect?
Wind dominates most of the year; stack effect takes over on still, cold days.
What do I need to enter into the Wind Pressure on Vent Calculator?
Just 3 values: wind speed, pressure coefficient, opening area. 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 Wind Pressure on Vent Calculator work out the answer?
Wind pressure grows with the square of wind speed and is modified by a surface pressure coefficient. It applies the formula P = 0.00256 x V² x Cp (psf, mph) and shows the working so you can check each step by hand.
Is the Wind Pressure on Vent 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.