Custom Size Furnace Filters
PureFilters pleated furnace filters in less common sizes such as 14x16x1, 20x23x1, 12x16x2 and 24x25x4. Most listings offer MERV 8, MERV 11 and MERV 13, in 12-packs for 1 and 2 inch filters and 6-packs for 4 inch filters. Measure your current filter and pick the matching size.
See how custom size furnace air filters work, or browse all furnace filters in standard sizes.
Custom size furnace filter guide: measuring, MERV and pack sizes ▾
Measure before you order
The size printed on a filter frame is usually its nominal size, rounded up from the actual measurements. Read the size on your old filter, or measure length, width and depth, then choose the listing that matches. Our guide to nominal vs actual filter sizes explains the difference.
Which MERV rating
MERV 8 is a common choice for everyday dust and lint. MERV 11 captures finer particles such as pet dander, and MERV 13 captures finer particles again. Higher MERV filters can restrict airflow on some systems, so check your furnace manual if you are unsure. See the MERV rating guide for a comparison.
Pack sizes and depths
- 1 inch and 2 inch custom sizes: 12-packs, for example 16x22x1, 24x30x1 and 21x22x2.
- 4 inch custom sizes: 6-packs, for example 16x22x4, 20x23x4, 15x25x4 and 12x20x4.
- The 30x36x1 is a 3-pack in MERV 8 and MERV 11.
Check a 1 inch filter about every 1 to 3 months; deeper filters usually last longer.
