If you already have a well-fitting filter, simply measure the width and length and provide that to us. Some manufacturers will print the actual size on the filter. Some filter manufacturs put the “nominal size” on their filters and not the actual size. We always recommend you confirm the size by measuring with a tape measure.

Please provide the actual size of the opening where the filter goes. Be sure to allow clearance for any tabs in the opening.

Many filter manufacturers will print a “Nominal” size on their filters which is larger than the actual size of the filters. Other manufacturers will put both the nominal size and actual size on their filters (See image). The larger of the two sizes is the nominal size. Because each filter manufacturer treats this differently, we recommend that you use the ACTUAL FILTER SIZE whenever possible.