4" MERV 11 Furnace & AC Air Filter by Filters Fast® - 3-Pack
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actual size

*Please be advised that some larger filters require an additional cost (see dropdown window above).

  • Size Actual Dimension
  • 12x24x4 11.375" x 23.375" x 3.625"
  • 16x20x4 15.5" x 19.5" x 3.625"
  • 16x25x4 15.5" x 24.5" x 3.625"
  • 18x24x4 17.375" x 23.375" x 3.625"
  • 20x20x4 19.5" x 19.5" x 3.625"
  • 20x24x4 19.375" x 23.375" x 3.625"
  • 20x25x4 19.375" x 24.375" x 3.625"
  • 24x24x4 23.375" x 23.375" x 3.625"
  • 25x29x4 24.375" x 28.375" x 3.625"

4" MERV 11 Furnace & AC Air Filter by Filters Fast® - 3-Pack


Only $27.65 per Filter
Retail: $99.99 /ea
You Save: 17%
As low as
Retail: $99.99
You Save: 17%
FF4M11 Sizes :
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The 4" MERV 11 Furnace & AC Air Filter by Filters Fast® - 3-Pack is a set of MERV 11 filters that effectively reduce pollen, dust, pet dander, mold spores, dust mites and other allergens from indoor air. Removing these airborne particles can help improve allergies and alleviate sinus irritation that can cause watery eyes, itchy throat, coughing, and sneezing. The MERV 11 filter media is electrostatically charged and constructed with spun micro-fiber that also will not retain moisture, which can lead to microbial growth. Aside from the health benefits, these HVAC filters will also extend the life of your heating and cooling system by making it work more efficiently.

Note: These filters do not contain fiberglass.


  • Brand: Filters Fast®
  • Part Number: FF4M11
  • Pack Size: 3
  • Filter Life: 6 - 12 Months
  • MERV Rating: 11
  • Filter Type: Electrostatic pleated
  • Material: Synthetic
  • For commercial and residential use

Available Sizes:

The 4" MERV 11 Furnace & AC Air Filter by Filters Fast® is available in the following sizes:

Nominal Size Actual Size Alternate Part Number
12x24x4 Air Filter 11.375x23.375x3.625 PF11.0412243PFF
16x20x4 Air Filter 15.375x19.375x3.625 PF11.0416203PFF
16x25x4 Air Filter 15.375x24.375x3.625 PF11.0416253PFF
18x24x4 Air Filter 17.375x23.375x3.625 PF11.0418243PFF
20x20x4 Air Filter 19.375x19.375x3.625 PF11.0420203PFF
20x24x4 Air Filter 19.375x23.375x3.625 PF11.0420243PFF
20x25x4 Air Filter 19.375x24.375x3.625 PF11.0420253PFF
24x24x4 Air Filter 23.375x23.375x3.625 PF11.0424243PFF
25x29x4 Air Filter 24.375x28.375x3.625 PF11.0425293PFF

Custom Sizes:

  • If you don' t see your size, order a custom made air filter! Custom made air filters do not come individually wrapped.

How do you install the 4" MERV 11 Furnace & AC Air Filter by Filters Fast®?

  1. Once your air filters arrive, gather your supplies including a ladder (if needed,) safety goggles, gloves, a mask, and a disposable bag.
  2. Remove the metal grate from your air return.
  3. Carefully remove the used air filter and place it immediately and gently into the disposable bag. Then tie the bag sealed.
  4. Place the new air filter in place of the filter you just removed and replace the metal grille.

How often should you replace the 4" MERV 11 Furnace & AC Air Filter by Filters Fast®?

  • Changing your 4" MERV 11 Furnace & AC Air Filter by Filters Fast® is a very quick and easy process that should be done once every six to twelve months.

What contaminants does the 4" MERV 11 Furnace & AC Air Filter by Filters Fast® reduce?

  • The 4" MERV 11 Furnace & AC Air Filter by Filters Fast® is a MERV 11 air filter, which means that it reduces the following contaminants:

    • Dust
    • Pollen
    • Mold Spores
    • Pet Dander
    • Dust Mites
    • Smoke & Smog
    • Other Common Airborne Allergens

Compatible Parts:

The 4" MERV 11 Furnace & AC Air Filter by Filters Fast® - 3-Pack is the correct replacement for the following part numbers:

Part Number
Aprilaire 261
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Customer Reviews:

Total Reviews: 67 | Average Rating: 4.85 / 5.0


It is a good product for my forced air heating.

Collected by Trustpilot.com

Recommend by manufacturer

Collected by Trustpilot.com
Jean Pieske2023-08-04

Comes delivered to my home and does a good job.

Collected by Trustpilot.com
Stephen Bailey2023-07-02

All good, will provide farther information after use.

Collected by Trustpilot.com
Dave Yates2023-06-11

works well for me

Collected by Trustpilot.com
Jay Andersen2023-06-06

Good filters.

Collected by Trustpilot.com

Really great price and is exactly what I need for my Air Handler

Collected by Trustpilot.com
Ian H.2023-04-21

Hard size to find locally 16x20x4! They fit perfectly in my air handler up in the attic and 2 spares for later.

Collected by Trustpilot.com
PHILLIP REED2023-04-04

Great value and convenient to order online. No guessing what you might find in a box store.

Collected by Trustpilot.com
Murry Card Jr2023-04-03

Does the job well.

Collected by Trustpilot.com

The filters work nicely, fit as expected and were delivered quickly.

Collected by Trustpilot.com
D S2023-03-31


Collected by Trustpilot.com
Rich Bonito2023-01-24

I change my filter quarterly, necessary or not, so it is good to have a "case" of filters from Filters Fast on hand.

Collected by Trustpilot.com
Barac Wimberly2023-01-16

Correct filters fit perfectly.

Collected by Trustpilot.com
Vince Harris2023-01-07

Fast Affordable & Quality

Collected by Trustpilot.com

They didnt fit! not even close to the right size - much smaller in all dimensions and wont fit in the slot in my AC unit.

Collected by Trustpilot.com
Jimmy Allcorn2022-12-20

Helps out with my alergys. We have dogs and you can't tell by the smell. Last 3 month for me. I change the filter may work longer for most people

Collected by Trustpilot.com

They filter heater and air utility very well, however, I never thought I’d pay $95.00 for basically a paper and cardboard product. Times are a changing…

Collected by Trustpilot.com
Robert Uland2022-11-15

Slightly smaller than original.

Collected by Trustpilot.com

Love the filters we use, good price and quality, with fast service. We'll be ordering again from this wonderful company

Collected by Trustpilot.com

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