How to Measure Your Filter
Steps 1 & 2
Measuring Length and Width (L x W). (If your filter is not a square, the smallest measurement goes first).


Step 3
Measure the thickness (Depth) of your filter from front to back.

Step 4
Put Your measurements together (L x W x D).

Actual Size
A filter’s true dimensions.
Example: 19.75” x 19.75” x 1”
Nominal Size
Rounded numbers used by manufacturers.
Example 20” x 20” x 1”
View Detailed Instructions