FilterBySize Furnace and AC filter sizes, actual dimensions, MERV

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25x25x1 air filter: actual size, MERV, and price

A 25x25x1 is a one-inch-class square furnace or AC filter. Buy the printed size 25x25x1. The panel is smaller than 25 inches on each face — Filtrete closer to 24.81 × 24.81 × 0.81 or 24.69 × 24.69 × 0.81, and Nordic Pure about 24.5 × 24.5 × 0.75. Do not substitute 24x24x1 or 20x25x1 — those are different printed sizes.

Actual size by brand

These numbers are copied from manufacturer or merchant product copy, not from a competitor size chart. Thickness is part of the fit: 1-inch racks take ~¾ inch media.

Brand Nominal Published actual (in.) Source
Filtrete 25x25x1 MPR 1000 / MERV 11 25x25x1 24.81 × 24.81 × 0.81 Amazon B07FNQT9ZY title “Actual Size 24.81 × 24.81 × 0.81 in”; product-dimensions field “24.81 × 0.81 × 24.81”
Filtrete 25x25x1 MPR 1000 / MERV 11 (some listings) 25x25x1 Title: 24.688 × 24.688 × 0.813; 4-pack dimensions field 24.69 × 24.69 × 0.81 Amazon B09YY5Y4M1 title “Actual Size 4-Pack 24.688×24.688×0.813 in”; product-dimensions field lists 24.69 × 24.69 × 0.81 — two figures on the same family; measure if the slot is tight
Filtrete 25x25x1 MPR 700 / MERV 8 25x25x1 24.81 × 24.81 × 0.81 Amazon B0DLPZ8GHR title “Actual Size 24.81 × 24.81 × 0.81 in”; product-dimensions field lists 24.81 × 24.81 × 0.81. Same actual on B0DKYZ6D8D 6-pack title
Filtrete 25x25x1 MPR 1500 / MERV 12 25x25x1 24.81 × 24.81 × 0.78 Amazon B07FP5X128 title “Actual Size 24.81 × 24.81 × 0.78 in”; product-dimensions field “24.81 × 0.78 × 24.81”
Nordic Pure 25x25x1 pleated 25x25x1 Approximately 24.5 × 24.5 × 0.75 (24½ × 24½ × ¾) JB Tools listings for Nordic Pure 25x25x1M8-6, 25x25x1M8-2, 25x25x1M13-6, and 25x25x1M13-2

We did not find a Honeywell Store 25x25x1 1-inch SKU (MERV 8/11/13 4-pack or 12-pack) that publishes actual dimensions, so that brand is omitted rather than guessed. We did not find an Amazon Basics 25x25x1 listing that publishes an actual-size field, so that brand is omitted rather than guessed. We did not find a Filtrete 25x25x1 MPR 1900 / MERV 13 listing that prints an actual-size field, so that grade is omitted rather than guessed. If you currently run Nordic Pure (~24.5 square) and switch to Filtrete (~24.81 or 24.69 square), expect a snugger slide-in. Filtrete’s published actuals also disagree with each other by SKU. Measure the old filter if the slot is tight. Full method: how to measure.

MERV 8 vs 11 vs 13 (facts only)

MERV is ASHRAE 52.2, as summarized by EPA. Higher MERV captures a larger share of smaller particles. It also adds resistance. EPA says to pick at least MERV 13 or as high a rating as your system fan and filter slot can accommodate, and to ask an HVAC technician if you are unsure. A 1-inch MERV 13 is not HEPA. We do not claim health outcomes.

MERV EPA average capture efficiency (particle size) Typical 25x25x1 use
8 ≥20% of 1.0–3.0 µm; ≥70% of 3.0–10.0 µm Common pleated replacement when the manual does not call for higher
11 ≥20% of 0.30–1.0 µm; ≥65% of 1.0–3.0 µm; ≥85% of 3.0–10.0 µm Mid-grade 1-inch pleat (Filtrete MPR 1000 is commonly labeled MERV 11)
13 ≥50% of 0.30–1.0 µm; ≥85% of 1.0–3.0 µm; ≥90% of 3.0–10.0 µm Higher-efficiency 1-inch; confirm the furnace/air handler can take the extra pressure drop

Source: U.S. EPA, “What is a MERV rating?”, last updated 14 Jan 2026. Filtrete also prints an MPR number; MPR is 3M’s scale, not MERV. Compare MERV to MERV.

Pack prices checked 30 Aug 2026

These are public shelf/cart prices we recorded on 30 Aug 2026. They are not live. Shipping, subscribe-and-save, and store-only deals will move them. Per-filter math is pack price ÷ count, rounded to the cent.

Listing MERV Pack Price that day Per filter Merchant
Nordic Pure 25x25x1 pleated (reseller) 8 2 $30.59 $15.30 JB Tools
Nordic Pure 25x25x1 pleated (reseller) 8 6 $53.99 $9.00 JB Tools
Nordic Pure 25x25x1 pleated (reseller) 13 2 $36.89 $18.45 JB Tools
Nordic Pure 25x25x1 pleated (reseller) 13 6 $80.99 $13.50 JB Tools

Observed range that day for ordinary pleated 25x25x1: about $9.00/filter at MERV 8 in a Nordic Pure 6-pack, $13.50 at MERV 13 in a Nordic Pure 6-pack, with 2-packs costing more per filter ($15.30 MERV 8; $18.45 MERV 13). Honeywell Store product URLs for 25x25x1 MERV 8/11/13 4-packs and 12-packs returned 404, so those rows are omitted rather than guessed. Target listed a Filtrete 25x25x1 MPR 1000 1-pack (A-14695648); that product page timed out and Target’s price API was not usable, so that pack price is omitted rather than guessed. Walmart Filtrete product pages were not used for this check (Target Filtrete preferred). Amazon Filtrete pages were used for actual-size fields, not for this price table. Amazon Basics had no published 25x25x1 actual-size listing. Nordic Pure’s own 25x25x1 factory cart was not used for a 1-inch SKU in this check; the JB Tools figures are reseller snapshots. A 25x25x1 is not a 24x24x1 or a 20x25x1.

Where to buy

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No ranking. Stock and price change. If the slot is an odd fraction that none of these actual sizes match, measure first — that is not a 25x25x1 SKU. A 24x24x1 or 20x25x1 is not a substitute.

Sources (accessed 30 Aug 2026)