PadMatch / Every humidifier water panel and furnace filter size
- Nominal size
- 16 x 25 x 4 in
- Actual size
- 15.375 x 24.375 x 3.625 in
- Depth class
- 4 in (media cabinet)
- Typically installed on
- media-cabinet air cleaners bolted to the furnace return (Aprilaire 1410/2410/4400, Honeywell F100)
- Sold in MERV
- sold in MERV 8, 11 and 13 as pleated media
Nominal versus actual dimensions for the 16 x 25 x 4 in furnace and HVAC air filter.
A 16 x 25 x 4 in furnace filter has an actual size of 15.375 x 24.375 x 3.625 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.
A four-inch deep pleated media filter for a whole-house filter cabinet, not a return grille. It seats in a dedicated media cabinet such as an Aprilaire 1410/2410 or Honeywell F100. A one-inch filter will not seal in this cabinet.
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 4 in actual sizenominal vs actual dimensions
- 20 x 25 x 4 in furnace filteractual 19.75 x 24.25 x 3.625 in
- Aprilaire 413 media filterAprilaire 413
- Honeywell FC100A1029 media filterHoneywell FC100A1029
- MERV 8 vs 11 vs 13 for a furnace filterwhich rating to buy
Sources: Atomic Filters nominal vs actual air filter size chart ยท AprilAire 413 MERV 13 pleated filter for 1410/2410/3410/4400 (Home Depot)