FilterBySize Furnace and AC filter sizes, actual dimensions, MERV

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20x25x4 air filter: actual size, MERV, and price

A 20x25x4 is a four-inch media filter for a dedicated cabinet — not a 1-inch slot. Do not substitute a 20x25x1. Do not mix it up with 20x25x5. Buy the printed size 20x25x4. The panel is smaller than 20 by 25 by 4 inches. Honeywell F100/F200 replacements (FC100A1037) are commonly published around 19.88 × 24.88 × 4.38; some Filtrete SKUs print 19.88 × 24.63 × 4.31; Nordic Pure’s 20x25x4 is about 19.5 × 24.5 × 3.63.

Same panel, swapped axes: 25x20x4. We treat 20x25x4 as the canonical label. Order 20x25x4.

Four-inch actual depth varies more by brand than 1-inch thickness does. Measure the old cartridge before you order. Common cabinet: Honeywell F100/F200 (replacement cartridge FC100A1037).

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: a Honeywell F100/F200 cabinet is built around a ~4⅜ inch cartridge, not a 3⅝ inch “4-inch” cut.

Brand Nominal Published actual (in.) Source
Honeywell FC100A1037 MERV 11 (F100/F200 media cabinet) 20x25x4 19⅞ × 24⅞ × 4⅜ (19.875 × 24.875 × 4.375) Air Quality Honeywell Store “Exact Dimensions” for FC100A1037. Other merchant copy prints ~19.94 × 24.86–24.88 × 4.38
Honeywell Home CF100A1025 MERV 8 3-pack 20x25x4 19.94 × 24.87 × 4.38 Amazon B098ZNWHSK title “Actual Dimensions: 19.94 × 24.87 × 4.38 in.”
Honeywell Home CF200A1016 MERV 12 3-pack 20x25x4 19.9 × 24.9 × 4.38 Amazon B098ZP4MNV title “Actual Dimensions: 19.9 × 24.9 × 4.38 in.”
Honeywell Home CF200A1016 (discontinued store listing) 20x25x4 19.38 × 24.38 × 4.37 Honeywell Store CF200A1016 product specs (page marked discontinued). Disagrees with the Amazon 3-pack title for the same model number; measure if the cabinet is tight
Filtrete 20x25x4 MPR 1000 / MERV 11 20x25x4 19.88 × 24.63 × 4.31 Amazon B09RQCX5YR title and “exact dimensions” 19.88 in × 24.63 in × 4.31 in
Filtrete 20x25x4 MPR 1550 / MERV 12 20x25x4 19.88 × 24.63 × 4.31 Amazon B09RQCWV3L title “Actual Size 19.88×24.63×4.31 in”
BestAir Honeywell 20x25x4 replacement MERV 8 3-pack 20x25x4 19¾ × 24¾ × 4¼ (19.75 × 24.75 × 4.25) Target A-79298928 product copy “Actual Size: 19 3/4 × 24 3/4 × 4 1/4”
BestAir Honeywell 20x25x4 replacement MERV 11 3-pack 20x25x4 19¾ × 24⅝ × 4¼ (19.75 × 24.625 × 4.25) Target A-79298922 product copy “Actual Size: 19 3/4 × 24 5/8 × 4 1/4”
Nordic Pure 20x25x4 pleated 20x25x4 Approximately 19.5 × 24.5 × 3.63 (19½ × 24½ × 3⅝) JB Tools listings for 20x25x4M8-2, 20x25x4M8-6, 20x25x4M13-2, and 20x25x4M13-6. Nordic Pure tells Honeywell cabinet owners needing 4⅜ inch depth to order their 20x25x5 Honeywell replacement instead (published 19.63 × 24.88 × 4.38)

If you currently run Nordic Pure’s 20x25x4 (~19.5 × 24.5 × 3.63) and switch to a Honeywell F100/F200 cartridge (~4.38 deep), the depth difference is about ¾ inch — that is not a snugger 1-inch slide-in; it is a different cabinet fit. Filtrete’s published 4.31 depth and BestAir’s 4.25 are closer to Honeywell’s 4.38 than Nordic Pure’s 3.63 is. Measure the old filter. 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 4-inch MERV 13 is not HEPA. We do not claim health outcomes.

MERV EPA average capture efficiency (particle size) Typical 20x25x4 use
8 ≥20% of 1.0–3.0 µm; ≥70% of 3.0–10.0 µm Common media-cabinet replacement when the manual does not call for higher (Honeywell Home CF100A1025 is labeled MERV 8)
11 ≥20% of 0.30–1.0 µm; ≥65% of 1.0–3.0 µm; ≥85% of 3.0–10.0 µm Honeywell FC100A1037 OEM rating; 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 4-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. Honeywell also sells a MERV 12 CF200A1016 20x25x4; that SKU is in the price table, not in this EPA 8/11/13 grid.

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 20x25x4 pleated (reseller; actual depth 3.63) 8 6 $112.49 $18.75 JB Tools
Nordic Pure 20x25x4 pleated (reseller; actual depth 3.63) 8 2 $42.74 $21.37 JB Tools
BestAir Honeywell 20x25x4 replacement 8 3 $79.99 $26.66 Target
Nordic Pure 20x25x4 pleated (reseller; actual depth 3.63) 8 1 $30.14 $30.14 JB Tools
Honeywell Home CF100A1025 20x25x4 8 3 $120.99 $40.33 Amazon
Filtrete 20x25x4 MPR 1000 Allergen Defense 11 2 $43.99 $22.00 Amazon
BestAir Honeywell 20x25x4 replacement 11 3 $102.99 $34.33 Target
Honeywell FC100A1037 11 4 $200.00 $50.00 Air Quality Honeywell Store
Honeywell FC100A1037 11 2 $115.00 $57.50 Air Quality Honeywell Store
Honeywell FC100A1037 11 1 $67.50 $67.50 Air Quality Honeywell Store
Honeywell Home CF200A1016 20x25x4 12 3 $109.99 $36.66 Amazon
Nordic Pure 20x25x4 pleated (reseller; actual depth 3.63) 13 6 $152.99 $25.50 JB Tools
Nordic Pure 20x25x4 pleated (reseller; actual depth 3.63) 13 2 $56.69 $28.35 JB Tools

Observed range that day: Nordic Pure’s 3.63-inch-deep 20x25x4 was about $18.75–$30.14/filter at MERV 8 and $25.50–$28.35 at MERV 13 — cheaper, and not the Honeywell F100/F200 4.38-inch cartridge. For cabinet-depth (~4.25–4.38) packs: BestAir MERV 8 3-pack $26.66, Honeywell Home MERV 8 3-pack $40.33, Filtrete MERV 11 2-pack $22.00, BestAir MERV 11 3-pack $34.33, Honeywell FC100A1037 OEM $50–$67.50, Honeywell Home MERV 12 3-pack $36.66. Amazon Basics had no 20x25x4 SKU with a printed actual, so that brand is omitted. Target Filtrete pages that loaded were a refillable 2-pack (A-94713073) for Filtrete’s own frame (published 19.88 × 24.62 × 4.25), not a standard Honeywell cartridge — omitted from the pack table rather than treated as a drop-in. Target BestAir MERV 13 (A-84064316) loaded without a public cart price, so that pack is omitted. Walmart Filtrete product pages were not used for prices (prefer Target; several Walmart fetches are bot-checked on this site). Home Depot Honeywell CF200D2025 was Akamai-blocked, so that pack price is omitted rather than guessed. Honeywell Consumer Store 20x25x4 URLs 404’d; the CF200A1016 page on Honeywell Store is marked discontinued and had no live price.

Where to buy

We may earn a commission if you buy through links on this page. It does not change the price you pay.

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 20x25x4 SKU. A 20x25x1 or 20x25x5 is not a substitute unless the published actual depth matches the old cartridge.

Sources (accessed 30 Aug 2026)