Best 4-Inch Furnace Filter (2026): What Fits Your Aprilaire, Honeywell or Lennox

Find the model number on the metal filter cabinet next to your furnace, or on your old filter. Then find it in the first column.

"Sold as" is the size on the box. The real size is what has to fit. Aprilaire filters are much longer than the box says: Aprilaire lists the 213 at 26 5/8 inches long and the 413 at 29 3/8. Lennox filters are sold as 5-inch, but Lennox lists them at 4 3/8 inches deep.

Honeywell does not publish the real size of its FC100 filters, so we show what the genuine Honeywell listing on Amazon says. For the 16 × 20 filter, Honeywell's product page says MERV 10 and its F100 brochure says MERV 11.

Cost per year = price per filter × filters per year. Price per filter = the Amazon price ÷ the filters in the pack, read November 11, 2026. Every maker here allows up to 12 months a filter, so we count one a year. Honeywell says every 6 to 12 months; at 6 months, double its cost.^[14][7]

"Best-selling copy" is the one with the best Amazon sales rank in Furnace Filters on November 11, 2026. "Check fit" means its listing gives a size more than 1/4 inch smaller, or more than 1/8 inch bigger, than the genuine filter on some side. Compatible sizes are the listing's own words; we have not measured them.

In an Aprilaire cabinet, no. A standard 20 × 25 × 4 filter is made for a 25-inch slot. Aprilaire lists its 213 at 26 5/8 inches long, so a standard filter leaves at least 1 5/8 inches open at the end of the rails, and air goes through the gap instead of the filter. A standard 16 × 25 × 4 in a 2410 leaves at least 4 3/8 inches open.^[1][3]

Even the copies made for Aprilaire list shorter lengths. Filtrete's 213 replacement lists 25 3/16 inches, about 1 7/16 inches shorter than Aprilaire's figure. Filtrete says it fits these cabinets. Aprilaire says off-brand filters "will not meet AprilAire standards for airflow, filtration, and efficiency." We have not put one in a cabinet. If you try one, look for a gap at the end of the rails.^[1][14]

In a Honeywell F100 or a Lennox HCC cabinet, a standard 4-inch filter is too thin. These cabinets take filters about 4 3/8 inches deep, which is why other brands sell them as "5-inch". Look for one sold as 20x25x5 (or 16x25x5), or a filter made for Honeywell or Lennox cabinets, that lists about 4 3/8 inches deep.^[6][14]

If your furnace has a plain 4-inch slot with no brand cabinet, any filter in the size printed on your old one is fine.

Buy MERV 13 if your cabinet has one. A 4-inch filter has far more pleated media than a 1-inch filter, so air moves through it slowly and meets less resistance. Aerostar's spec sheet for its Green Pleat MERV 13 lists the same filter at three depths, tested at 375 and 500 feet per minute of air speed (inches of water, lower is easier on your blower):^[10]

At the same airflow, the 4-inch MERV 13 starts at about half the resistance of the 1-inch one. The U.S. Department of Energy notes that a filter with 4-inch pleats has twice the surface area of one with 2-inch pleats.^[11]

The cabinet makers' own numbers are low too. Aprilaire lists 0.08 inches of resistance at 1,000 cfm for a 2210 with MERV 13 media. Lennox lists 0.26 inches for its MERV 13 filter at 492 feet per minute, a hair less than its MERV 11 filter (0.27).^[5][6]

The EPA suggests MERV 13, or as high as your system can take. Skip MERV 16 unless an HVAC tech checks your blower first: Lennox lists its MERV 16 filter at 0.31 inches, the highest of its three.^[12][6]

Every genuine and compatible media filter we priced, by cabinet: MERV, listed size, fit, pack and Amazon price

Filter	MERV	Size	Pack	Per filter	Buy
Aprilaire 20 × 25 (2210, 1210, 3210, 4200)
Aprilaire 210, 2‑packGenuine part	11	20 5/8 × 26 5/8 × 4 in.	2	$59.97	$119.93
Aprilaire 213, 2‑packGenuine part	13	20 5/8 × 26 5/8 × 4 in.	2	$62.99	$125.98
Filtrete 213 replacement, 2‑packCheck fit: 1 7/16 in. shorter	13	20 3/8 × 25 3/16 × 3 3/4 in.	2	$32.30	$64.60
Filtrete 210 replacement, 2‑packCheck fit: 1 7/16 in. shorter	11	20 3/8 × 25 3/16 × 3 3/4 in.	2	$36.10	$72.20
Soulmate 213 replacement, 2‑packCheck fit: size not listed	13	not listed	2	$36.49	$72.99
UNIREACH 213 replacement, 2‑packCheck fit: 1 in. shorter	13	20 1/2 × 25 5/8 × 3 15/16 in.	2	$39.99	$79.99
UNIREACH 210 replacement, 2‑packCheck fit: 1 in. shorter	11	20 1/2 × 25 5/8 × 3 15/16 in.	2	$39.99	$79.99
Filtrete 210 replacementCheck fit: 1 7/16 in. shorter	11	20 3/8 × 25 3/16 × 3 3/4 in.	1	$49.99	$49.99
Filtrete 213 replacementCheck fit: 1 7/16 in. shorter	13	20 3/8 × 25 3/16 × 3 3/4 in.	1	$50.00	$50.00
Aprilaire 16 × 25 (2410, 1410, 3410, 4400)
Aprilaire 410, 2‑packGenuine part	11	16 1/2 × 29 3/8 × 4 in.	2	$56.49	$112.99
Aprilaire 413, 2‑packGenuine part	13	16 1/2 × 29 3/8 × 4 in.	2	$62.99	$125.98
Filtrete 413 replacement, 2‑packCheck fit: 1 9/16 in. shorter	13	16 1/8 × 27 13/16 × 3 3/4 in.	2	$34.00	$68.00
Soulmate 410 replacement, 2‑packCheck fit: 1 3/8 in. shorter	11	16 × 28 × 4 in.	2	$34.99	$69.99
BETTFILTER 410 replacement, 2‑packCheck fit: size not listed	11	not listed	2	$38.49	$76.99
BETTFILTER 413 replacement, 2‑packCheck fit: size not listed	13	not listed	2	$39.49	$78.99
Filtrete 410 replacement, 2‑packCheck fit: 1 9/16 in. shorter	11	16 1/8 × 27 13/16 × 3 3/4 in.	2	$42.48	$84.97
Filtrete 413 replacementCheck fit: 1 9/16 in. shorter	13	16 1/8 × 27 13/16 × 3 3/4 in.	1	$49.99	$49.99
Honeywell F100 / F200, 20 × 25
Honeywell FC100A1037, 2‑packGenuine part	11	19 15/16 × 24 7/8 × 4 3/8 in.	2	$27.00	$54.00
Filtrete 20x25x4 for Honeywell, 2‑packFits: within 1/4 in.	11	19 7/8 × 24 5/8 × 4 5/16 in.	2	$27.50	See Homequip on Amazon
Filterbuy 20x25x5 MERV 11, 2‑packFits: within 1/8 in.	11	19 7/8 × 24 3/4 × 4 3/8 in.	2	$29.49	$58.98
Filterbuy 20x25x5 MERV 13, 3‑packFits: within 1/8 in.	13	19 7/8 × 24 3/4 × 4 3/8 in.	3	$29.99	$89.97
Nordic Pure 20x25x5, 2‑packFits: same size	13	19 7/8 × 24 7/8 × 4 3/8 in.	2	$40.99	$81.99
Honeywell F100 / F200, 16 × 25
Honeywell FC100A1029Genuine part	11	15 15/16 × 24 7/8 × 4 3/8 in.	1	$38.99	$38.99
Filterbuy 16x25x5, 4‑packFits: within 3/16 in.	11	15 3/4 × 24 3/4 × 4 3/8 in.	4	$24.49	See AirPurete on Amazon
Filtrete 16x25x4 for Honeywell and Lennox, 2‑packCheck fit: 5/16 in. shorter	11	15 7/8 × 24 9/16 × 4 5/16 in.	2	$24.98	$49.97
Nordic Pure 16x25x5, 2‑packFits: within 3/16 in.	12	15 3/4 × 24 3/4 × 4 3/8 in.	2	$28.50	$56.99
Honeywell F100 / F200, 16 × 20
Honeywell FC100A1003, 2‑packGenuine part	10	not listed	2	$26.50	$53.00
Filterbuy 16x20x5, 2‑packCheck fit: no genuine size to compare	11	15 3/4 × 19 3/4 × 4 3/8 in.	2	$35.49	$70.98
Lennox HCC20-28
Filtrete 20x25x5 for Lennox, 2‑packFits: within 1/8 in.	11	19 5/8 × 24 3/4 × 4 5/16 in.	2	$24.96	$49.92
Filterbuy 20x25x5 MERV 11, 2‑packFits: within 1/8 in.	11	19 7/8 × 24 3/4 × 4 3/8 in.	2	$29.49	$58.98
Filterbuy 20x25x5 MERV 13, 3‑packFits: within 1/8 in.	13	19 7/8 × 24 3/4 × 4 3/8 in.	3	$29.99	$89.97
Nordic Pure 20x25x5, 2‑packFits: within 1/8 in.	13	19 7/8 × 24 7/8 × 4 3/8 in.	2	$40.99	$81.99
Lennox HCC16-28
Lennox X6670, 2‑packGenuine part	11	15 3/4 × 24 3/4 × 4 3/8 in.	2	$30.18	$60.36
Filterbuy 16x25x5, 4‑packFits: same size	11	15 3/4 × 24 3/4 × 4 3/8 in.	4	$24.49	See AirPurete on Amazon
Filtrete 16x25x5 for Lennox, 2‑packFits: within 1/8 in.	11	15 5/8 × 24 3/4 × 4 5/16 in.	2	$25.00	See AirPurete on Amazon
Nordic Pure 16x25x5, 2‑packFits: same size	12	15 3/4 × 24 3/4 × 4 3/8 in.	2	$28.50	$56.99

Genuine sizes are the maker's own, except Honeywell (the genuine listing's). Compatible sizes and MERV are each listing's own words. Prices read live November 11, 2026.

What is the best 4-inch furnace filter?

The one made for your cabinet. For an Aprilaire 2210, the genuine Aprilaire 213 ($62.99 a filter on Amazon, MERV 13, one a year). For a Lennox HCC20-28, the Filtrete 20x25x5 for Lennox ($24.96 a filter). For a Honeywell F100 20 × 25, the genuine Honeywell FC100A1037 ($27.00 a filter). ^[1][6][14]

What can I use instead of an Aprilaire 213?

Filtrete and others sell 213 replacements for less, but every copy that lists a size is shorter than Aprilaire's 26 5/8 inches (Filtrete's: 25 3/16), and some list no size. Aprilaire's MERV 11 version, the 210, fits the same cabinets ($59.97 a filter on Amazon on November 11, 2026). ^[1][2][14]

What is the difference between the Aprilaire 213 and 413?

Size. The 213 fits the 20 × 25 cabinets (2210, 1210, 3210, 4200) and Aprilaire lists it at 20.6 × 26.63 × 4 inches. The 413 fits the 16 × 25 cabinets (2410, 1410, 3410, 4400) at 16.52 × 29.38 × 4 inches. Both are MERV 13 and last 12 months. The 210 and 410 are the MERV 11 versions. ^[1][3]

Is MERV 13 too restrictive in a 4-inch filter?

Usually not. Aerostar's Green Pleat MERV 13 starts at 0.22 inches of resistance at 4 inches deep, against 0.45 at 1 inch deep, both at 375 feet per minute. That is a faster air speed than the state test on our Filtrete vs Nordic Pure page, so these numbers run higher. Lennox lists its MERV 13 cabinet filter at 0.26 inches, slightly less than its MERV 11. Change it on schedule. ^[10][5][6]

How often should I change a 4-inch furnace filter?

Aprilaire says every 12 months, Lennox says up to 12 months, and Honeywell says every 6 to 12 months. A 1-inch filter needs changing far more often: Aprilaire's own guide says its 1-inch filter lasts up to 6 months. ^{[1][6][7][13]}

Can I use a 4-inch filter in a 5-inch Lennox cabinet?

Not a standard one. Lennox lists its X6673 at 19 3/4 × 24 3/4 × 4 3/8 inches. A standard 4-inch filter is about 3 3/4 inches deep, so it leaves a gap. Buy one sold as 20x25x5 that lists about 4 3/8 inches deep. ^[6][14]

Is a Honeywell FC100A1037 the same as a 20x25x5 filter?

Close. The genuine FC100A1037 listing on Amazon gives 19.94 × 24.88 × 4.38 inches, and many filters sold as 20x25x5 list about 19 7/8 × 24 3/4 × 4 3/8. That is why sellers list one filter for both Honeywell and Lennox. Honeywell itself does not publish the real size. ^[8][14]

• Best furnace filter for your size (1-inch and 4-inch)
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1. 1

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

   Read October 22, 2026. "Actual Measurements: 20.6H x 26.63W x 4D (inches)"; "MERV Rating: 13"; "Recommended Replacement Schedule: 12 Months"; compatible models; "Off-brand filter options will not meet AprilAire standards"; the new UK213 "replace[s] your existing 213 Filter".

2. 2

   AprilAire: 210 Replacement Filter (shop.aprilaire.com)

   Read October 22, 2026. Same 20.6H x 26.63W x 4D actual size, MERV 11, 12 months, same compatible models.

3. 3

   AprilAire: 413 Replacement Filter (shop.aprilaire.com)

   Read October 22, 2026. "Actual Measurements: 16.52H x 29.38W x 4D (inches)"; MERV 13; 12 months; fits 1410, 1610, 2410, 2416, 3410, 4400.

4. 4

   AprilAire: 410 Replacement Filter (shop.aprilaire.com)

   Read October 22, 2026. Same 16.52H x 29.38W x 4D actual size, MERV 11, 12 months.

5. 5

   AprilAire (Research Products): Model 2410 / 2210 media air cleaner specification sheet

   Initial airflow resistance with MERV 13 media: 2210 .08 in. w.c. at 1,000 cfm, .22 at 2,000 cfm; 2410 .09 at 1,000 cfm, .27 at 2,000 cfm. "Collapsible media with integrated self-spacing pleats."

6. 6

   Lennox: Healthy Climate HCC media air cleaners, product specifications (form 210450, Feb 2024)

   Read October 22, 2026. HCC16-28 takes X6670 (MERV 11), 19L16 (MERV 13), X6672 (MERV 16): actual 15-3/4 x 24-3/4 x 4-3/8 in. HCC20-28 takes X6673, 19L17, X6675: actual 19-3/4 x 24-3/4 x 4-3/8 in. Service life "Up to 12 months". Pressure drop at 492 fpm: 0.27 in. w.c. (MERV 11), 0.26 (MERV 13), 0.31 (MERV 16).

7. 7

   Honeywell: F100 and F200 whole-house media air cleaners (literature 50-9091, 2016)

   Read October 22, 2026. Cabinet sizes: F100F2028 16x20, F100F2002 16x25, F100F2036 20x20, F100F2010 20X25 (F200F same numbers). "Replace every 6-12 months versus monthly or quarterly changes." No real (measured) filter size is printed.

8. 8

   Resideo (Honeywell Home): 20 in x 25 in MERV 11 Replacement Media Filter FC100A1037

   Read October 22, 2026. MERV 11. "Works with Honeywell Home Whole House Electronic Air Cleaners F25, F27, F35, F100, F150 and F200." The 16 x 25 (FC100A1029) page says the same.

9. 9

   Resideo (Honeywell Home): 16 in x 20 in MERV 10 Replacement Media Filter FC100A1003

   Read October 22, 2026. Page title says MERV 10; Honeywell's F100 literature rates the F100 media MERV 11.

10. 10

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

    Read October 22, 2026. Initial resistance, 24 x 24 face: 1-inch 0.45 in. w.g. at 375 fpm; 2-inch 0.25 at 375, 0.39 at 500; 4-inch 0.22 at 375, 0.34 at 500. Recommended final resistance 1.0 in. w.g.

11. 11

    U.S. Department of Energy, Building America: California Energy Standards Recognize the Importance of Filter Selection

    Read October 22, 2026. "a filter with 4-in. pleats has twice the surface area of one with a 2-in. pleats"; a filter drop of 0.25 in. w.c. "can account for half of the system's allotted 0.5 in. WC."

12. 12

    U.S. EPA: Guide to Air Cleaners in the Home

    "At least MERV 13 or as high as your system will accommodate"; most systems take MERV 13 if the filter is changed on time.

13. 13

    AprilAire: Air Filter Guide

    Read October 22, 2026. "One filter lasts up to 12 months (3") and up to 6 months (1")."

14. 14

    Amazon listings: pack, MERV and size as each listing states them; sales rank in Furnace Filters

    31 listings. Price, seller and stock read from each Amazon product page on November 11, 2026; sales rank from Amazon the same day.