Evaporative Cooler Pad Area Calculator
Pad face area needed for a swamp cooler's airflow.
Enter your values
Enter the fan airflow in CFM.
Enter the design face velocity in FPM.
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.
- Required pad area
- 20 sq ft
- 4x4 ft pad sections needed
- 1.3
- Water bleed-off rate guide
- 1.6 GPM
Quick answer
Evaporative cooler pads should be sized so air passes through at roughly 150-250 feet per minute face velocity for good cooling.
Pad area = CFM / face velocity
At a glance
| What it does | Pad face area needed for a swamp cooler's airflow. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Fan airflow, Design face velocity |
| Main output | Required pad area |
| Formula | Pad area = CFM / face velocity |
| Cost | Free — no sign-up, no download |
How to use the Evaporative Cooler Pad Area Calculator
- 1Take the evaporative cooler's rated fan airflow in CFM.
- 2Divide by a target face velocity of 150-250 FPM.
- 3Add pad sections or panel width until the required area is met.
Inputs explained
- Fan airflow(CFM)
- Enter the fan airflow in CFM.
- Design face velocity(FPM)
- Enter the design face velocity in FPM.
Worked example
Using the values the calculator loads with:
Inputs
- Fan airflow4000 CFM
- Design face velocity200 FPM
Results
- Required pad area20 sq ft
- 4x4 ft pad sections needed1.3
- Water bleed-off rate guide1.6 GPM
Frequently asked questions
What happens with too little pad area?
Air moves through too fast, saturation drops and cooling effectiveness falls sharply.
Rigid vs aspen pads?
Rigid cellulose pads tolerate higher velocities (up to 500 FPM) than loose aspen fiber pads.
What do I need to enter into the Evaporative Cooler Pad Area Calculator?
Just 2 values: fan airflow, design face velocity. 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 Evaporative Cooler Pad Area Calculator work out the answer?
Evaporative cooler pads should be sized so air passes through at roughly 150-250 feet per minute face velocity for good cooling. It applies the formula Pad area = CFM / face velocity and shows the working so you can check each step by hand.
Is the Evaporative Cooler Pad Area 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.