Step 1: Find Square Inches

Measure the actual size of the two sides of your filter, convert to a decimal, and multiply to get the square inches. DO NOT USE SIZES WRITTEN ON THE FILTERS WITHOUT MEASURING. Sizes written on the side of the filter are usually not the actual size.

____A____" X __B____" = ____?____"

Example: 16 1/4" x 25" = 16.25 x 25 = 406.25 sq

Step 2: Click on the selection your size fits within

Less than 149"
150-199"
200-249"
250-299"
300-399"
400-499"
500-599"
600-699"
700-799"
800-899"
900-999"

Note: If both dimensions are larger than 24 3/4", or if either dimension is larger than 35" it is considered a double size filter. Double size filters can not be figured using this method. Please call 877-345-8375 and speak to a representative for a price.