Evaporative Cooler Pad Area Calculator
Pad face area needed for a swamp cooler's airflow.
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ⓘ Live results
Results
- 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
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.
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.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.