What MERV should I buy for a 20x25x1 furnace?

MERV 11 for most homes: $6.21 a filter here, $0.27 less than MERV 8. The EPA says to choose at least MERV 13 or as high as your system will accommodate, and MERV 13 costs $2.46 more a filter than MERV 11.

Will MERV 13 work in my furnace?

The EPA says most furnaces take MERV 13 without problems when the filter is changed often. If your manual names a lower top MERV, buy MERV 11 and keep the $2.46 a filter.

What is the real size of a 20x25x1 filter?

Real size is 19.5 to 19.75 inches by 24.5 to 24.75, and 0.75 deep. Modern Air Filters lists about 19.5 x 24.5 x 0.75; the Simply and Aerostar listings print 19.75 x 24.75 x 0.75 and BNX prints 19.69 x 24.69 x 0.75. Measure your slot, or look for 20x25x1 on your old filter.

Can I use a 20x25x2 filter in a 20x25x1 slot?

No. A 20x25x2 filter is twice as deep as a 20x25x1 slot, so match all three numbers on the edge of your old filter.

How often should I change a 20x25x1 filter?

The EPA says makers recommend a new 20x25x1 filter every 60 to 90 days. At $6.21 a MERV 11 filter, that is $25 to $37 a year. Change a 20x25x1 sooner with pets, smoke or a lot of dust.

Is a bigger pack of 20x25x1 filters cheaper?

For MERV 11, the Amazon Basics 6-pack is $6.21 a filter and the lowest-priced bigger pack, the Filterbuy 12-pack, is $7.66. A 12-pack of 20x25x1 is 2 to 3 years of filters, so the 6-pack is the one to buy.

Best 20x25x1 Furnace Filter

Buy the Amazon Basics 20x25x1 MERV 11 6-pack: $6.21 a filter on November 11, 2026, or $25 to $37 a year. For allergies or pets, buy the Aerostar MERV 13 6-pack at $8.67 a filter, if your furnace manual allows MERV 13.^[1]

See Aerostar on Amazon

MERV 8

MERV 8 catches dust, lint and pollen at $6.48 a filter. MERV 11 costs $0.27 less today, so buy MERV 11.

Amazon Basics 20x25x1, 6-pack

$6.48 per filter

$38.85 for 6 · about $26 to $39 a year

A 6-pack of 20x25x1 lasts about 1 to 1.5 years.

Bigger pack, lower price per filter: Filtrete 12-pack, $5.44 each ($65.31).

Check price on Amazon

MERV 11

MERV 11 catches fine dust, mold spores and pet dander, and costs $0.27 less a filter than MERV 8.

Amazon Basics 20x25x1, 6-pack

$6.21 per filter

$37.26 for 6 · about $25 to $37 a year

A 6-pack of 20x25x1 lasts about 1 to 1.5 years.

See Aerostar on Amazon

MERV 13

MERV 13 also catches smoke and bacteria, at $2.46 more a filter than MERV 11.

Aerostar 20x25x1, 6-pack

$8.67 per filter

$51.99 for 6 · about $35 to $52 a year

A 6-pack of 20x25x1 lasts about 1 to 1.5 years.

Check price on Amazon

20x25x1 price per filter is the buy-box price divided by the filters in the pack, read November 11, 2026.^[3]

By Erin Rose · Updated November 11, 2026

Filtrete vs Filterbuy vs our pick, 20x25x1

Filtrete MERV 11 (MPR 1000) is $10.35 a filter in a 2-pack, $4.14 more than our pick, about $41 to $62 a year. Filterbuy MERV 11 is $7.66 a filter in a 12-pack, about $31 to $46 a year.^[3]

Filtrete, Filterbuy and our pick for 20x25x1: pack, price per filter and cost a year
Filter	Pack	Per filter	A year	Buy
Our pick: Amazon Basics 20x25x1, MERV 11	6	$6.21	$25 to $37	See Aerostar on Amazon
Filterbuy 20x25x1, MERV 11	12	$7.66	$31 to $46	See Aerostar on Amazon
Filtrete 20x25x1 MPR 1000, MERV 11	2	$10.35	$41 to $62	See Aerostar on Amazon
Our pick: Aerostar 20x25x1, MERV 13	6	$8.67	$35 to $52	Check price
Filterbuy 20x25x1, MERV 13	12	$8.83	$35 to $53	See Aerostar on Amazon
Filtrete 20x25x1 MPR 1900, MERV 13	6	$12.22	$49 to $73	See Aerostar on Amazon

A year of 20x25x1 is 4 to 6 filters (a change every 60 to 90 days). Each row is the lowest 20x25x1 price per filter we read for that brand and MERV on November 11, 2026.

What 20x25x1 means, and what it measures

The label is the size you order by, and a real 20x25x1 filter is a little smaller, so it slides in.^[4]

Read the edge of your old filter. It should say 20x25x1: width, height, depth.
Depth matters. A 20x25x2 or 20x25x4 filter is too thick for a 1-inch slot. A 20x25x1 that fits leaves no gap and is not bent or crushed.^[1]
Will MERV 13 work in your furnace? Check the highest MERV on your furnace label or in its manual. MERV 11 saves $2.46 a filter over MERV 13, and a year of MERV 11 runs $25 to $37.

MERV 8, 11 or 13 in 20x25x1: what each catches and what it costs

MERV 13 costs $2.19 more per filter than MERV 8 and $2.46 more than MERV 11. The picks above run $6.48 for MERV 8, $6.21 for MERV 11 and $8.67 for MERV 13.^[3]

MERV is a lab score (ASHRAE 52.2), and each 20x25x1 filter below carries one of these three numbers; this EPA table gives the least a filter must trap to earn it.^[2]

Minimum capture efficiency by particle size for MERV 8, 11 and 13 (EPA)
MERV	Smallest, 0.3–1 microns (smoke, bacteria)	Fine, 1–3 microns (fine dust, mold spores)	Large, 3–10 microns (pollen, dust)
8	not required	20% or more	70% or more
11	20% or more	65% or more	85% or more
13	50% or more	85% or more	90% or more

The EPA sets one minimum for each MERV number, whatever the brand, and a 20x25x1 filter of about 19.5 x 24.5 inches is held to the same one. Paying more for the same MERV buys a brand name, not a different minimum. MERV is printed by each maker. Filtrete uses its own MPR scale; to convert, see What MERV rating do I need?

All 20x25x1 filters, lowest price per filter first

20x25x1 furnace filters on Amazon with MERV, pack, price and price per filter
Filter	MERV	Pack	Price	Per filter	Buy
Filtrete	8	12	$65.31	$5.44	Check price
Amazon Basics	11	6	$37.26	$6.21	See Aerostar on Amazon
Amazon Basics	8	6	$38.85	$6.48	Check price
Filterbuy	8	12	$77.88	$6.49	Check price
Aerostar	11	6	$41.40	$6.90	Check price
Filter King	8	6	$44.94	$7.49	Check price
BNX	8	6	$44.96	$7.49	Check price
Filterbuy	11	12	$91.92	$7.66	See Aerostar on Amazon
BNX	11	6	$49.48	$8.25	See BNX on Amazon
Aerostar	13	6	$51.99	$8.67	Check price

Show all 19 20x25x1 filters

The rest of the 20x25x1 furnace filters on Amazon, by price per filter
Filter	MERV	Pack	Price	Per filter	Buy
Frigidaire	8	6	$52.49	$8.75	Check price
Filterbuy	13	12	$105.96	$8.83	See Aerostar on Amazon
Simply	11	6	$56.97	$9.49	See Aerostar on Amazon
Filterbuy	8	4	$38.96	$9.74	Check price
BNX	11	4	$38.96	$9.74	Check price
BNX	13	6	$58.59	$9.77	See Aerostar on Amazon
Simply	13	6	$59.27	$9.88	See Aerostar on Amazon
Filtrete	11	2	$20.69	$10.35	See Aerostar on Amazon
Filtrete	13	6	$73.31	$12.22	See Aerostar on Amazon

Each 20x25x1 filter's size, MERV and pack count come from its listing title. 20x25x1 prices read November 11, 2026; they change, so the button shows today's.

Frequently asked

What MERV should I buy for a 20x25x1 furnace?: MERV 11 for most homes: $6.21 a filter here, $0.27 less than MERV 8. The EPA says to choose at least MERV 13 or as high as your system will accommodate, and MERV 13 costs $2.46 more a filter than MERV 11. ^[2]^[1]
Will MERV 13 work in my furnace?: The EPA says most furnaces take MERV 13 without problems when the filter is changed often. If your manual names a lower top MERV, buy MERV 11 and keep the $2.46 a filter. ^[1]
What is the real size of a 20x25x1 filter?: Real size is 19.5 to 19.75 inches by 24.5 to 24.75, and 0.75 deep. Modern Air Filters lists about 19.5 x 24.5 x 0.75; the Simply and Aerostar listings print 19.75 x 24.75 x 0.75 and BNX prints 19.69 x 24.69 x 0.75. Measure your slot, or look for 20x25x1 on your old filter. ^[4]^[3]
Can I use a 20x25x2 filter in a 20x25x1 slot?: No. A 20x25x2 filter is twice as deep as a 20x25x1 slot, so match all three numbers on the edge of your old filter.
How often should I change a 20x25x1 filter?: The EPA says makers recommend a new 20x25x1 filter every 60 to 90 days. At $6.21 a MERV 11 filter, that is $25 to $37 a year. Change a 20x25x1 sooner with pets, smoke or a lot of dust. ^[1]
Is a bigger pack of 20x25x1 filters cheaper?: For MERV 11, the Amazon Basics 6-pack is $6.21 a filter and the lowest-priced bigger pack, the Filterbuy 12-pack, is $7.66. A 12-pack of 20x25x1 is 2 to 3 years of filters, so the 6-pack is the one to buy. ^[3]

Where these numbers come from

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"; makers "typically recommend replacement every 60 to 90 days"; the filter should fit snugly, with no bending or crushing.
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
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
Modern Air Filters: 20x25x1 air filter
Read November 3, 2026. Actual size about 19.5 x 24.5 x 0.75 inches; order by the nominal 20x25x1; MERV 8, 11 and 13 pleated filters; a pleated filter typically lasts 60 to 90 days.