FilterBySize Furnace and AC filter sizes, actual dimensions, MERV

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Size page

This is a first-pass size page: actual size and MERV, not the full pack-price table yet. The complete 16x25x1 page is the model. Next full page in the shipping order is 20x20x1.

20x25x1 air filter: actual size and MERV

A 20x25x1 is a one-inch-class filter. Same panel as 25x20x1; we treat 20x25x1 as the canonical label.

Actual size by brand

BrandPublished actual (in.)Source
Honeywell 1-inch Ultra Efficiency MERV 13 and High Efficiency MERV 1119.75 × 24.75 × 0.75Honeywell Store product specs
Amazon Basics 20x25x1 MERV 8 6-pack19.75 × 24.75 × 0.75Amazon product title
Amazon Basics MERV 5 20x25x1 6-pack19.75 × 24.75 × 0.75Amazon B0DQPF65SW title
Filtrete 20x25x1 MPR 2200 / MERV 1319.69 × 24.69 × 0.78Amazon B07FPB8H31 “exact dimensions”
Filtrete 20x25x1 MPR 1000 / MERV 11 (one listing)19.68 × 24.68 × 0.81Amazon product title “Actual Size 19.68 × 24.68 × 0.81 in”

MERV 8 / 11 / 13

MERV does not change the nominal size. EPA’s table (ASHRAE 52.2):

MERVEPA average capture efficiency
8≥20% of 1.0–3.0 µm; ≥70% of 3.0–10.0 µm
11≥20% of 0.30–1.0 µm; ≥65% of 1.0–3.0 µm; ≥85% of 3.0–10.0 µm
13≥50% of 0.30–1.0 µm; ≥85% of 1.0–3.0 µm; ≥90% of 3.0–10.0 µm

EPA: if you upgrade, use at least MERV 13 or as high as the system fan and slot can take. Check the HVAC manual before MERV 13 in a 1-inch slot. MERV 13 is not HEPA. No health claims.

How to measure   See the 16x25x1 page for a full buy table

Sources (accessed 30 Aug 2026). EPA: What is a MERV rating?. Brand actual sizes: Honeywell Store product specs and Amazon product titles/“actual size” fields cited on this page.