Best 20x25x4 Furnace Filter

Buy the Aerostar 20x25x4 MERV 13 6-pack: $20.16 a filter on November 11, 2026. The 6-pack is $120.99 and lasts about 3 to 6 years. If your furnace manual tops out at MERV 11, buy the Aerostar MERV 11 6-pack at $11.32 a filter.[1]

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Aerostar 20x25x4 MERV 8 furnace filter

MERV 8

MERV 8 catches dust, lint and pollen at $12.00 a filter. MERV 11 costs $0.68 less today, so buy MERV 11.

Aerostar 20x25x4, 6-pack

$12.00 per filter

$71.99 for 6 · about $12 to $24 a year

A 6-pack of 20x25x4 lasts about 3 to 6 years.

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Aerostar 20x25x4 MERV 11 furnace filter

MERV 11

MERV 11 catches fine dust, mold spores and pet dander, and costs $0.68 less a filter than MERV 8.

Aerostar 20x25x4, 6-pack

$11.32 per filter

$67.94 for 6 · about $11 to $23 a year

A 6-pack of 20x25x4 lasts about 3 to 6 years.

Smaller pack: Simply 4-pack, $16.87 each ($67.47).

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Aerostar 20x25x4 MERV 13 furnace filter

MERV 13

MERV 13 also catches smoke and bacteria, at $8.84 more a filter than MERV 11.

Aerostar 20x25x4, 6-pack

$20.16 per filter

$120.99 for 6 · about $20 to $40 a year

A 6-pack of 20x25x4 lasts about 3 to 6 years.

Smaller pack: Aerostar 4-pack, $23.50 each ($93.99).

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20x25x4 price per filter is the buy-box price divided by the filters in the pack, read November 11, 2026.[3]

By Erin Rose · Updated

Filtrete vs Filterbuy vs our pick, 20x25x4

Filtrete MERV 11 (MPR 1000) is $21.91 a filter in a 4-pack, $10.59 more than our pick, about $22 to $44 a year. Filterbuy MERV 11 is $17.74 a filter in a 12-pack, about $18 to $35 a year.[3]

Filtrete, Filterbuy and our pick for 20x25x4: pack, price per filter and cost a year
FilterPackPer filterA yearBuy
Aerostar 20x25x4 MERV 11 furnace filterOur pick: Aerostar 20x25x4, MERV 11 6 $11.32 $11 to $23 Check price
Filterbuy 20x25x4 MERV 11 furnace filterFilterbuy 20x25x4, MERV 11 12 $17.74 $18 to $35 See Homequip on Amazon
Filtrete 20x25x4 MERV 11 furnace filterFiltrete 20x25x4 MPR 1000, MERV 11 4 $21.91 $22 to $44 See Homequip on Amazon
Aerostar 20x25x4 MERV 13 furnace filterOur pick: Aerostar 20x25x4, MERV 13 6 $20.16 $20 to $40 Check price
Filterbuy 20x25x4 MERV 13 furnace filterFilterbuy 20x25x4, MERV 13 12 $20.41 $20 to $41 Check price
Filtrete 20x25x4 MERV 13 furnace filterFiltrete 20x25x4 MPR 1900, MERV 13 2 $36.02 $36 to $72 Check price

A year of 20x25x4 is 1 to 2 filters (a change every 6 to 12 months, per Filterbuy). Each row is the lowest 20x25x4 price per filter we read for that brand and MERV on November 11, 2026.

What 20x25x4 means, and what it measures

19.5 × 24.5 real size, inches label: 20 × 25 depth: label 4 in, real about 3.63 in
The label is the size you order by, and a real 20x25x4 filter is a little smaller, so it slides in.[4]
  • Find 20x25x4 on your old filter or the cabinet. It should read 20x25x4. Filterbuy lists its 20x25x4 at 19.5 x 24.5 x 3.63 inches, a little under the label, so it slides in.
  • Depth matters. A 20x25x1 or 20x25x2 leaves a gap that air goes around. A good fit sits snug, with no gap and no bending.[1]
  • Your cabinet may take its own part. Check the part number printed on the cabinet; the 4-inch filter guide lists the part for each Aprilaire, Honeywell and Lennox cabinet.
  • An Aprilaire 213 is sold as a 20x25x4 but listed larger. Aprilaire's shop lists the 213 at 20.6 x 26.63 x 4 inches under the nominal 20 x 25 x 4. Other retailers print other sizes for it, so match the Aprilaire part number on your cabinet, not the nominal size.[6]
  • Will MERV 13 work in your furnace? Check the top MERV on the furnace or cabinet label first. The MERV 13 pick costs $8.84 more a filter than MERV 11, or $20 to $40 a year against $11 to $23.

MERV 8, 11 or 13 in 20x25x4: what each catches and what it costs

MERV 13 costs $8.16 more per filter than MERV 8 and $8.84 more than MERV 11. The picks above run $12.00 for MERV 8, $11.32 for MERV 11 and $20.16 for MERV 13.[3]

MERV is a lab score (ASHRAE 52.2). This EPA table is the least a MERV 8, 11 or 13 filter must trap, whether it is 1 inch deep or 4.[2]

Minimum capture efficiency by particle size for MERV 8, 11 and 13 (EPA)
MERVSmallest, 0.3–1 microns (smoke, bacteria)Fine, 1–3 microns (fine dust, mold spores)Large, 3–10 microns (pollen, dust)
8not required20% or more70% or more
1120% or more65% or more85% or more
1350% or more85% or more90% or more

We priced 28 20x25x4 listings today, from $11.32 a filter (Aerostar) to $36.02 (Filtrete). Filterbuy builds its 4-inch filters to last 6 to 12 months, and Aprilaire says 12 for its 213, so a year costs one or two filters. To convert Filtrete's MPR numbers, see What MERV rating do I need?

All 20x25x4 filters, lowest price per filter first

20x25x4 furnace filters on Amazon with MERV, pack, price and price per filter
FilterMERVPackPricePer filterBuy
Aerostar 11 6 $67.94 $11.32 Check price
Aerostar 8 6 $71.99 $12.00 Check price
Filterbuy 8 12 $179.88 $14.99 Check price
AirPurete 8 6 $89.99 $15.00 Check price
Simply 11 4 $67.47 $16.87 See Homequip on Amazon
Filterbuy 8 6 $103.98 $17.33 Check price
Filter King 8 5 $86.90 $17.38 Check price
Filterbuy 11 12 $212.88 $17.74 See Homequip on Amazon
Filterbuy 8 5 $88.95 $17.79 Check price
AirPurete 8 4 $74.88 $18.72 Check price
Show all 28 20x25x4 filters
The rest of the 20x25x4 furnace filters on Amazon, by price per filter
FilterMERVPackPricePer filterBuy
Filterbuy 8 4 $74.96 $18.74 Check price
Filterbuy 11 4 $79.16 $19.79 See Homequip on Amazon
Aerostar 13 6 $120.99 $20.16 Check price
Filter King 11 6 $121.98 $20.33 See Homequip on Amazon
Filterbuy 13 12 $244.92 $20.41 Check price
Filterbuy 11 6 $122.94 $20.49 See Homequip on Amazon
Nordic Pure 8 6 $124.99 $20.83 Check price
Filterbuy 11 5 $104.95 $20.99 See Homequip on Amazon
Filtrete 11 4 $87.65 $21.91 See Homequip on Amazon
Filterbuy 13 6 $139.98 $23.33 Check price
Aerostar 13 4 $93.99 $23.50 Check price
Filterbuy 13 5 $119.95 $23.99 Check price
AIRx 11 6 $149.34 $24.89 See Homequip on Amazon
Filterbuy 13 4 $99.96 $24.99 Check price
BNX 13 4 $105.99 $26.50 Check price
AIRx 13 6 $165.74 $27.62 Check price
Unbranded 11 2 $67.99 $33.99 Check price
Filtrete 13 2 $72.04 $36.02 Check price

Each 20x25x4 filter's size, MERV and pack count come from its listing title. 20x25x4 prices read November 11, 2026; they change, so the button shows today's.

Frequently asked

Which MERV goes in a 20x25x4 cabinet?
MERV 13 at $20.16 a filter (Aerostar 6-pack) if your cabinet allows it. The EPA says to choose MERV 13 or the highest your system accommodates, and Aerostar lists its MERV 13 at 0.22 inches of water resistance in 4-inch against 0.45 in 1-inch. If the cabinet maker says MERV 11, buy the Aerostar 6-pack at $11.32 a filter. [1][5]
How big is a 20x25x4 filter really?
Real size is 19.5 x 24.5 inches and 3.63 deep. Filterbuy lists its 20x25x4 at 19.5 x 24.5 x 3.63, and other makers print slightly different sizes. Measure your cabinet, or look for 20x25x4 on your old filter. [4][3]
Is an Aprilaire 213 the same as a 20x25x4?
Aprilaire sells the 213 as a nominal 20 x 25 x 4, and its shop lists it at 20.6 x 26.63 x 4 inches. Other retailers print other sizes for it. Use the Aprilaire part number for your cabinet; the 4-inch filter guide lists the part for each Aprilaire, Honeywell and Lennox cabinet. [6]
How often does a 20x25x4 need changing?
Filterbuy says its 4-inch filters are built to last 6 to 12 months, and Aprilaire says every 12 months for its 213. At $20.16 a MERV 13 filter that is $20 to $40 a year. Pets, smoke and heavy dust push you toward the early end. [4][6]
Can a 1-inch filter go in a 4-inch cabinet?
Not safely. A 20x25x1 leaves a wide gap in a cabinet built for 4 inches, so air goes around it. Buy the 20x25x4 printed on your old filter.
How many 20x25x4 filters should I buy?
The Aerostar 6-pack is $20.16 a filter, $120.99 for the pack, and covers 3 to 6 years of changes. For a smaller outlay, the Aerostar MERV 13 4-pack is $93.99 ($23.50 each) and covers 2 to 4 years. [3]

Where these numbers come from

  1. 1

    U.S. EPA: Guide to Air Cleaners in the Home (furnace and HVAC filters)

    Read October 28, 2026. "Select a filter rated at least MERV 13 or as high as your system will accommodate"; "Most furnaces and HVAC systems can accommodate a MERV 13 filter without creating equipment problems, provided that the filter is replaced frequently"; the filter should fit snugly, with no bending or crushing.

  2. 2

    U.S. EPA: What is a MERV rating?

    Read October 28, 2026. The capture table below is copied from the EPA table for MERV 8, 11 and 13.

  3. 3

    Amazon.com product listings (size, MERV and pack from each listing title; price, seller and stock from the buy box)

    Buy boxes read November 11, 2026. Prices change; the button shows today's. Filtrete's MERV equivalents (MPR 1000 = MERV 11, MPR 1900 = MERV 13) are taken from each listing's title.

  4. 4

    Filterbuy: 20x25x4 air filters

    Read October 28, 2026. "Actual Size: 19.5x24.5x3.63"; "built to last 6 to 12 months"; sold in MERV 8, 11 and 13.

  5. 5

    Filtration Group: Aerostar Green Pleat MERV 13 specification sheet (1, 2 and 4 inch)

    Read October 22, 2026. Starting resistance at 375 feet per minute: 1-inch 0.45 inches of water, 4-inch 0.22.

  6. 6

    AprilAire: 213 Replacement Filter (shop.aprilaire.com)

    Read October 22, 2026. "Actual Measurements: 20.6H x 26.63W x 4D (inches)"; MERV 13; replace every 12 months. Other retailers print other actual sizes for this filter.

Related: furnace filters in every size · what MERV rating do I need? · is MERV 13 too restrictive? · 4-inch filters for Aprilaire, Honeywell and Lennox cabinets