PadMatch / Every humidifier water panel and furnace filter size
- Nominal size
- 20 x 20 x 1 in
- Actual size
- 19.5 x 19.5 x 0.75 in
- Depth class
- 1 in (flat panel)
- Order by
- nominal size (20 x 20 x 1 in)
- Typically installed on
- square return grilles and some horizontal air handlers
The true measured dimensions of a 20 x 20 x 1 in filter and how to order it.
The nominal size 20 x 20 x 1 in is the name on the frame; the actual size is 19.5 x 19.5 x 0.75 in. On a flat filter each face runs about half an inch under nominal and a one-inch filter is really three quarters of an inch thick.
A square flat filter, actual 19.5 by 19.5 by 0.75 inches. Because it is square, it can be installed in either rotation, which is why a 20 by 25 slot will not accept it and vice versa.
Find your model
Read the number stamped on the humidifier cabinet or printed on the old pad, then match it below. Confirm the frame size before buying a generic.
- 20 x 20 x 1 in furnace filteractual 19.5 x 19.5 x 0.75 in
- MERV 8 vs 11 vs 13which rating to buy
- 16 x 25 x 1 in actual sizeactual 15.5 x 24.5 x 0.75 in
- 20 x 25 x 1 in actual sizeactual 19.5 x 24.5 x 0.75 in
- 16 x 20 x 1 in actual sizeactual 15.5 x 19.5 x 0.75 in
Sources: Atomic Filters nominal vs actual air filter size chart ยท Filterbuy air filter sizes chart