16x25x4 Air Filter: Actual Size by Maker

Last updated: 2026-10-30

A pleated (folded) 16x25x4 air filter measures 15.5 x 24.5 x 3.63 in on a filter maker's product page, and another maker's 2026 bulletin prints it as 15-1/2 x 24-1/2 x 3-3/4 in. Some filters made for whole-house media cabinets with the same 16 x 25 face run deeper, 4.31 to 4.38 in. A cabinet maker's 2025 bulletin calls its deeper filter a 16 x 25 x 5.

“16x25x4” is the nominal size, the rounded name you order by. The actual size is what the filter measures. The face size is the height and width, without the depth. A media cabinet is a whole-house filter box next to the furnace that holds a thick filter. Read across for the actual size each maker prints.

The Size Each Maker Prints

*Decimals for Glasfloss and Lennox are our conversion of their fractions. The 3M row is our match of the two size lists on its product page. The other rows are as each maker prints them. H, W and D mean height, width and depth. MERV (Minimum Efficiency Reporting Value) is the industry filter rating; MPR is Filtrete's own rating scale.

The two pleated filters differ by about an eighth of an inch in depth: 3.63 in from Filterbuy and 3.75 in from Glasfloss. The 3M, Lennox and Carrier filters for media cabinets are deeper, 4.31 to 4.38 in. AprilAire's 413 is 4 in deep but 29.38 in wide for a 25 in nominal width. See AprilAire 2410 and the 413 filter.

Why a 16x25x4 May Not Fit a 16 x 25 Cabinet

Lennox calls its 4-3/8 in deep filter a 16 x 25 x 5. Resideo's guide prints Honeywell's FC100A1029 and FC200E1029 as 16 X 25 X 4 but gives no actual size. So the face size alone does not tell a 3.63 in pleated filter from a 4.31 to 4.38 in media filter. Measure the depth of your old filter before you order.

Sources: Lennox, Healthy Climate media air cleaners bulletin (PDF); Resideo, Honeywell Home Filter Replacement Guide 50-1312 (PDF).

How to Pick the Right 16x25x4

1. Read the size name and any part number on the frame of the filter you have now.
2. Measure its depth with a tape measure.
3. If it is about 3.6 to 3.75 in deep, a pleated 16x25x4 from the first two rows matches. If it is deeper than that, such as 4.3 to 4.4 in, find your cabinet maker's part number on the filter size by brand page.

Other ratings for the same size: Filterbuy lists its 16x25x4 at MERV 8, 11 and 13. Our Filtrete MPR to MERV chart converts 3M's MPR numbers.

Source: Filterbuy 16x25x4 product page.

Other sizes: 16x25x1, 20x25x4 and 20x20x1. See also: Honeywell Media Filters, Nominal vs. Actual Size. All Filter Sizes.

Sources

1. Filterbuy, 16x25x4 air filters product page (“Actual Size”, model AFB16x25x4M8): https://filterbuy.com/air-filters/16x25x4/
2. Glasfloss, Z-Line ZL series product bulletin 6ZLINEZL, dated 3/10/26 (PDF), “ZL Standard Size Filters” table: https://www.glasfloss.com/wp-content/uploads/2025/10/06baBro0326ZL.pdf
3. 3M, Filtrete MPR 1550 Allergen, Bacteria & Virus Air Filters (4” and 5” Lennox) product page (undated): https://www.filtrete.com/3M/en_US/p/d/b5005595006/
4. Lennox, Healthy Climate HCC media air cleaners bulletin, form 210450 (August 2025, PDF): https://www.lennox.com/dA/a1d2030a9b/ehb_hcc_2508.pdf
5. Carrier, FILCAB and FILCAR media filter product data, catalog FLCB-04PD (edition 09/11, PDF): https://ia.cappusa.com/ZDMaOBgxD3qjtL_-ggBhMr_7uu34GH9wHoWMtVnD/data-sheet-carrier-filcabxl0016-filcabxl0020-filcabxl0024-filxxcar0116-filxxcar0120.pdf
6. AprilAire, 413 MERV 13 Air Filter: https://shop.aprilaire.com/products/aprilaire-413-replacement-filter
7. Resideo, Honeywell Home Filter Replacement Guide, form 50-1312 (08/20, PDF): https://customer.resideo.com/resources/Techlit/TechLitDocuments/50-0000s/50-1312.pdf