The best 4-inch pleated air filter depends on your filter cabinet’s actual dimensions and the particle filtration level you want. Filtrete’s MERV 12 options are best for buyers prioritizing higher stated particle capture, while its MERV 11 filters and Honeywell’s MERV 11 models offer alternatives at different dimensions. Nordic Pure is a useful option when your system requires a shallower 3.63-inch actual depth. Always compare the filter’s actual size with your existing filter before ordering.
| Filter | Rating | Actual size | Best for |
|---|---|---|---|
| Filtrete 20x25x4 MERV 12 | MERV 12 | 19.88 x 24.63 x 4.31 in | 20×25 cabinets and higher stated capture |
| Honeywell FC100A1037 | MERV 11 | 19.94 x 24.88 x 4.38 in | Buyers matching this exact Honeywell size |
| Filtrete 16x25x4 MERV 12 | MERV 12 | 15.88 x 24.56 x 4.31 in | 16×25 cabinets and higher stated capture |
| Filtrete 16x25x4 MERV 11 | MERV 11 | 15.88 x 24.56 x 4.31 in | 16×25 cabinets and MERV 11 filtration |
| Nordic Pure 20x25x4 | MERV 12 | 19.5 x 24.5 x 3.63 in | Shallower 20×25 filter openings |
Filtrete 20x25x4 MERV 12
This two-pack of Filtrete filters is best for buyers whose media air cleaner calls for the listed 20×25 nominal size and whose cabinet fits the actual dimensions of 19.88 x 24.63 x 4.31 inches. It is rated MERV 12 and MPR 1550. The manufacturer says it helps capture 50% of small particles passing through the filter. The product is designed to fit Honeywell and AprilAire Space-Gard brand media air cleaners.
The pack is described as providing 12-month filters, but the appropriate replacement schedule can depend on the system and household conditions. Check the actual depth carefully: it is slightly over 4 inches.
Honeywell FC100A1037 MERV 11
This Honeywell two-pack is best for shoppers matching a 20×25 nominal filter opening that requires an actual size of 19.94 x 24.88 x 4.38 inches. It has a MERV 11 rating. Compared with the Filtrete 20×25 MERV 12 option, its listed actual width, height, and depth differ, so the product name alone is not enough to confirm a fit.
Choose this model if its actual dimensions match your cabinet and you want a MERV 11 filter. Avoid it if your cabinet cannot accommodate its 4.38-inch actual depth; the product details do not list additional filtration claims.
Filtrete 16x25x4 MERV 12
This two-pack is best for a 16×25 media air cleaner that fits an actual filter size of 15.88 x 24.56 x 4.31 inches. Filtrete lists it as MERV 12 and MPR 1550, and says it helps capture 50% of small particles passing through. Listed compatible media air cleaner brands include Honeywell, TrionAirBear, Bryant, Carrier, and Lennox.
It is a stronger fit for buyers seeking the listed higher rating in the 16×25 size than the matching Filtrete MERV 11 model below. Confirm your cabinet’s actual dimensions, since this filter is not a full 4 inches deep.
Filtrete 16x25x4 MERV 11
This Filtrete two-pack is best for 16×25 systems that take an actual 15.88 x 24.56 x 4.31-inch filter and call for MERV 11. It has an MPR 1000 rating and is listed for Honeywell and Lennox brand media air cleaners. Filtrete says its MERV 11/MPR 1000 filter helps capture up to two times more microparticles than MERV alone.
Its dimensions match the Filtrete 16×25 MERV 12 product, making the rating an important point of comparison. Choose this version when MERV 11 matches your needs; it is not the higher-rated option of the pair.
Nordic Pure 20x25x4 MERV 12
This two-pack is best for buyers whose 20×25 filter cabinet requires a shallower actual depth. Its actual dimensions are 19.5 x 24.5 x 3.63 inches, and it uses MERV-rated synthetic poly blend pleated media. That depth is substantially less than the actual depths of the listed Filtrete and Honeywell 20×25 options, so measure rather than assuming all products labeled 20x25x4 are interchangeable.
Nordic Pure advises measuring the existing filter and comparing the result with the actual size. Its product information also directs buyers replacing certain Honeywell or Lennox filters with a 4.38-inch actual depth to a 20x25x5 version instead.
Buying Guide: How to Choose a 4-Inch Pleated Filter
What size should you buy?
Use the actual dimensions printed on your current filter or measure it directly. Nominal sizes such as 16x25x4 and 20x25x4 are labels, not guarantees of exact width, height, or depth. A difference of several tenths of an inch can affect whether a filter seats properly. Compare all three dimensions, especially depth, before purchasing.
Should you choose MERV 11 or MERV 12?
The products listed here include both ratings. The Filtrete MERV 12 models also list MPR 1550 and a claim about capturing 50% of small particles passing through. The MERV 11 Filtrete models list MPR 1000 and a microparticle comparison. These claims are product-specific; compare the rating and manufacturer details while following any requirements for your HVAC system.
How do you check compatibility?
Start with the filter cabinet’s measurements and the model or brand information on your existing filter. Some listings identify compatible media air cleaner brands, but brand names do not replace checking dimensions. If a replacement filter is too shallow, too deep, or otherwise mismatched, it may not fit correctly.
When should you replace the filter?
Follow the replacement guidance for your HVAC equipment and inspect the filter according to the manufacturer’s instructions. Filtrete describes some of its two-packs as 12-month filters, but actual replacement timing may depend on system use and household conditions. Do not treat a product’s stated service period as a substitute for equipment guidance.
Frequently Asked Questions
Are all 4-inch pleated air filters exactly 4 inches deep?
No. These examples range from 3.63 to 4.38 inches in actual depth. Confirm the exact measurement for the filter you plan to buy.
Can I use any filter labeled 20x25x4?
No. Filters with the same nominal label can have different actual dimensions. Match the width, height, and depth to your cabinet.
What does MERV 12 mean in these listings?
MERV is the filtration rating shown for the product. The Filtrete MERV 12 listings also provide separate MPR information and manufacturer particle-capture claims.
Which listed filter is the shallowest?
The Nordic Pure 20x25x4 has the shallowest listed actual depth at 3.63 inches. Verify that its full actual dimensions fit your system.
Do these products come in multipacks?
Each of the five selected products is listed as a two-pack. Check the specific product listing for current packaging details before ordering.