Tool
Size Finder
Pick what you are replacing and the number on it. What comes back is the gap between the printed size and the measured one, or — for a purifier cartridge — what the listings for that code actually name.
What are you replacing
The size printed on the frame
20x25x1 — nominal against actual
In this catalog at that sizeMERV 11 and MERV 12
- Actual sizes differ between manufacturers at the same nominal name, so measure the filter you have and read the stated actual size on the listing you order from.
- Note which way the airflow arrow points before the old filter leaves the slot.
Actual sizes differ between manufacturers at the same nominal name. Whatever this tool shows, measure the filter you are holding and read the stated actual size on the listing you order from.
What this tool is doing
Nothing clever. It is a lookup against the same data every filter page on this site is built from, which means the actual dimensions it shows are the figures the listings state and nothing has been averaged, rounded, or inferred on the way through. Where this catalog holds no page for a size or a code, the tool says so rather than offering the nearest thing.
What it cannot do
- Tell you what a manufacturer outside this catalog states as an actual size, since that figure varies by maker at the same nominal name.
- Tell you whether a frame will seat in your slot, which depends on rails and retainers you have to look at.
- Tell you which rating your system takes. That stays with the equipment manufacturer documentation, and with a licensed HVAC professional where it cannot be found.