PadMatch / Every humidifier water panel and furnace filter size
- Nominal size
- 16 x 25 x 1 in
- Actual size
- 15.5 x 24.5 x 0.75 in
- Depth class
- 1 in (flat panel)
- Typically installed on
- the return-air grille or blower-door slot of a great many gas furnaces and air handlers built for a 16 by 25 return
- Sold in MERV
- sold flat-panel in MERV 8, 11 and 13
Nominal versus actual dimensions for the 16 x 25 x 1 in furnace and HVAC air filter.
A 16 x 25 x 1 in furnace filter has an actual size of 15.5 x 24.5 x 0.75 in. The label is the nominal size, rounded up so the filter is easy to name; the panel is cut undersize so it slides into the slot without binding.
The single most common flat furnace filter size. The actual panel is half an inch under nominal on each face and only three quarters of an inch thick, so it drops into a one-inch return-grille slot without binding.
Order by the nominal size printed on the old filter frame, not by measuring the slot, because every brand runs to the same nominal-to-actual convention.
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.
- 16 x 25 x 1 in actual sizenominal vs actual dimensions
- 20 x 25 x 1 in furnace filteractual 19.5 x 24.5 x 0.75 in
- 16 x 20 x 1 in furnace filteractual 15.5 x 19.5 x 0.75 in
- MERV 8 vs 11 vs 13 for a furnace filterwhich rating to buy
Sources: Atomic Filters nominal vs actual air filter size chart ยท American Standard: furnace filter sizes explained