Louver Free Area Adjuster
Convert required free area into actual louver or grille opening area using free-area percentage and simple opening shape estimates.
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Frequently asked questions
What is free area in a louver or grille?
Free area is the actual open area available for airflow through a louver or grille after accounting for blades, frame, screens, and other obstructions.
Why is the actual opening larger than the required free area?
Because louvers and grilles reduce the usable open area. If a product only provides a certain free-area percentage, the rough opening must be larger to achieve the required free area.
How do you calculate actual opening area from free area percentage?
Divide the required free area by the free-area ratio. For example, if required free area is 100 square inches and the louver provides 75 percent free area, the actual opening area must be about 133.3 square inches.
Should I use manufacturer free-area data?
Yes. Manufacturer free-area data should always be used when available because actual louver and grille performance varies by design.
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