FilterBySize Furnace and AC filter sizes, actual dimensions, MERV

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20x24x1 air filter: actual size, MERV, and price

A 20x24x1 is a one-inch-class rectangle furnace or AC filter. Buy the printed size 20x24x1. The panel is smaller than 20 by 24 inches — commonly 19.75 × 23.75 × 0.75, with Filtrete closer to 19.68 × 23.68 × 0.81 or 19.81 × 23.81 × 0.81 and Nordic Pure about 19.5 × 23.44 × 0.75 (19½ × 23 7/16 × ¾).

Same panel, swapped axes: 24x20x1. We treat 20x24x1 as the canonical label. Order 20x24x1. Do not substitute 16x24x1, 20x20x1, 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
Honeywell 1-inch Standard/High/Ultra Efficiency (MERV 8, 11, and 13) 20x24x1 19.75 × 23.75 × 0.75 Honeywell Store product specs (4-pack and 12-pack)
Filtrete 20x24x1 MPR 1000 / MERV 11 20x24x1 19.68 × 23.68 × 0.81 Amazon B07FPB8Q8M, B00TUDHMB8, and B001ETX3F0 titles “Actual Size 19.68 x 23.68 x 0.81 in”
Filtrete 20x24x1 MPR 1000 / MERV 11 (some listings) 20x24x1 19.81 × 23.81 × 0.81 Amazon B07FPB8Q8M, B00TUDHMB8, and B001ETX3F0 product-dimensions fields list 23.81 × 0.81 × 19.81
Filtrete 20x24x1 MPR 700 / MERV 8 20x24x1 19.81 × 23.81 × 0.81 Amazon B0DMTG6FPV title “Actual Size 19.81 x 23.81 x 0.81 in”
Filtrete 20x24x1 MPR 1900 / MERV 13 20x24x1 19.81 × 23.81 × 0.78 Amazon B07FPB8H11 title “Actual Size 19.81x23.81x0.78 in”; same-SKU product-dimensions field lists 23.81 × 0.78 × 19.81
Nordic Pure 20x24x1 pleated 20x24x1 Approximately 19.5 × 23.44 × 0.75 (19½ × 23 7/16 × ¾) JB Tools listing for Nordic Pure 20x24x1M8-24 and 20x24x1M13-24

We did not find an Amazon Basics 20x24x1 listing that publishes an actual-size field, so that brand is omitted rather than guessed. If you currently run Nordic Pure (~19.5 × 23.44) and switch to Honeywell (19.75 × 23.75), 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 20x24x1 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
Honeywell 20x24x1 Standard Efficiency 8 4 $28.95 $7.24 Honeywell Store
Honeywell 20x24x1 Standard Efficiency 8 12 $76.95 $6.41 Honeywell Store
Nordic Pure 20x24x1 pleated (reseller) 8 24 $176.39 $7.35 JB Tools
Honeywell 20x24x1 High Efficiency 11 4 $38.95 $9.74 Honeywell Store
Honeywell 20x24x1 High Efficiency 11 12 $104.95 $8.75 Honeywell Store
Honeywell 20x24x1 Ultra Efficiency 13 4 $60.95 $15.24 Honeywell Store
Honeywell 20x24x1 Ultra Efficiency 13 12 $170.95 $14.25 Honeywell Store
Nordic Pure 20x24x1 pleated (reseller) 13 24 $251.99 $10.50 JB Tools

Observed range that day for ordinary pleated 20x24x1: about $6.41–$7.35/filter at MERV 8 in multi-packs, $8.75–$9.74 at MERV 11, $10.50–$15.24 at MERV 13. Nordic Pure’s factory 20x24x1 configurator did not print a numeric actual in the fetch; the JB Tools figures are a reseller snapshot with published 19.5 × 23.44 × 0.75. Target Filtrete 20x24x1 product pages (A-14695650 MPR 1000 1-pack and A-51885735 MPR 1900) returned a bot check, so those pack prices are omitted rather than guessed. Walmart Filtrete product pages were not used for a cart price. Amazon Filtrete pages were used for actual-size fields, not for this price table. Amazon Basics had no published 20x24x1 actual-size listing.

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 20x24x1 SKU. A 16x24x1, 20x20x1, or 20x25x1 is not a substitute.

Sources (accessed 30 Aug 2026)