HVAC & Furnace Filters · United States

Your furnace filter, matched by size

Air filters are universal by size — read the numbers printed on the side of your old filter (width × height × depth) and pick that exact size below. We show the true dimensions, which MERV rating you actually need, and how often to change it.

Choose your size

Read the three numbers on the edge of your old filter, then tap that size for every MERV rating and depth with live prices.

10x20 12x12 12x20 12x24 12x30 12x36 14x14 14x18 14x20 14x24 14x25 14x30 15x20 16x16 16x20 16x24 16x25 16x30 18x18 18x20 18x24 18x25 18x30 20x20 20x24 20x25 20x30 20x36 22x22 24x24 24x30 25x25 30x30 30x36

Which MERV rating do you need?

Higher MERV traps finer particles — but pick the highest your system can handle without straining airflow.

MERV 8

Standard protection

Captures pollen, dust, lint, dust-mite debris and mold spores.

Best for everyday home use — the standard choice to protect your HVAC system. (MPR ~600, FPR 5.)

MERV 11

Allergy & pet

Captures everything MERV 8 does plus pet dander, fine dust and smog particles.

Best for homes with pets or mild allergies. (MPR ~1000–1200, FPR 7.)

MERV 13

Maximum filtration

Captures everything MERV 11 does plus smoke, bacteria and virus-carrying particles.

Best for allergy and asthma sufferers, and homes dealing with wildfire smoke. (MPR ~1500–1900, FPR 10.)

Shop by brand

Prefer a specific brand? Jump to its sizes and MERV options.

Filtrete Honeywell Nordic Pure Aerostar Filterbuy FilterKing

How to read your filter size

The size is printed on the cardboard edge of your current filter, e.g. 16x25x1 = 16" wide × 25" tall × 1" thick (nominal). The real filter measures about half an inch smaller so it slides in — that's normal. If your old filter has no printing, measure it and round to the nearest standard size above. Depth matters most: a 1" slot won't take a 4" media filter and vice-versa.