25x25x1 MERV 13 Furnace & AC Air Filter
The 25x25x1 (actual size 24.5 × 24.5 × 0.75 in) in MERV 13 — captures everything MERV 11 does plus smoke, bacteria and virus-carrying particles. Best for allergy and asthma sufferers, and homes dealing with wildfire smoke. Below: the true dimensions, when to change it, and how this MERV compares to the others that fit the same slot.
Same size, other MERV ratings
All fit your 25x25x1x1 slot — step up for finer filtration, down for easier airflow.
Measured your slot? Other depths
Depth must match your filter slot exactly. Same 25x25x1 face, different thickness.
Frequently asked questions
What is the actual size of a 25x25x1 air filter?
A 25x25x1 is the nominal size printed on the frame. The true measured size is about 24.5 × 24.5 × 0.75 in, cut slightly under so the filter slides into the 25x25 slot. This is standard across all brands.
What does MERV 13 filter out?
MERV 13 captures everything MERV 11 does plus smoke, bacteria and virus-carrying particles. It's best for allergy and asthma sufferers, and homes dealing with wildfire smoke. On the box you may see it labelled MPR ~1500–1900 (3M/Filtrete) or FPR 10 (Home Depot).
How often should I change a 25x25x1x1 filter?
Change it every 60–90 days. A 1" filter clogs quickest, so check it monthly. A clogged filter strains your blower and raises energy bills.
Will a 25x25x1x1 filter fit my furnace?
Air filters are universal by size — any furnace, AC or return grille that takes a 25x25x1x1 filter will fit this one, regardless of the HVAC brand. Just match the three numbers on your old filter's frame exactly, depth included.