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20x21x1 Air Filter Merv 8
20x21x1 AC Filter Merv 11
20x21x1 Furnace Filter Merv 13
20x21x1 Filter Merv 13 Titanium
20x21x1 Filter Merv 10 Carbon
20x21x1 Filter Merv 8 Carbon 20x21x1 Filter Merv 8 Carbon
Protects All Against
  • Pollen protection
  • Dust protection
  • Mold protection
  • Dust Mites protection
    Dust Mites
  • Bacteria protection
  • Pet Dander protection
    Pet Dander
  • Smoke protection
  • Viruses protection
  • Cooking Smoke protection
  • Odor protection
  • Smog protection
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20x21x1 Air Filter

AC Furnace Air Filter 20x21x1 -Inches

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Product Description

Item Model Number: FKFB20X21A
Brand: Filter King
Air Filter size: 20x21x1
Actual Size: 20 x 21 x .75
1-Inch Filter
MERV 8 Air Filter Rating
Protection From: Pollen, Household Dust, Mold Spores, Dust Mites mold, Bacteria, Pet Dander, Smoke, Viruses
Residential / Commercial Use

Manufactured in the US

Why Buy Air Filters From Filter King?


In comparison to fiberglass filters, 20x21x1 pleated air filters are at least 20 times more effective. All Filter King air filters are made in the US.


Filters frames are made out of heat resistant paperboard with horizontal grid supports. Able to withstand temperatures of up to 200° F and resistant to moisture, the paperboard frames do not support microbial growth and outperforms traditional cardboard frames.


Chemical free, electrostatically charged synthetic polyester media is pleated, maximizing the surface area, to capture a high number of airborne particles as small as 0.3 microns with low air flow resistance. To increase durability, the media is supported with a corrosion resistant steel wire.

20x21x1 Air Filter Reviews

What MERV Rating should I choose?

How Often to Change Your 20x21x1 Air Filter?

Filter King AC & furnace filters aren’t the typical fiberglass filters that need to be replaced every 30 days. Our filters can typically be used for 3 to 5 months before requiring to be changed. Naturally, a variety of things influence filter lifespan.

Some of the factors that influence your filter’s life include outdoor air quality, whether pets are in the home, and how well your HVAC system is maintained.

Your air filter becomes clogged over time by trapped particles, preventing airflow. The efficiency of the HVAC filter declines. Your system must work harder to heat and cool your home. The extra strain on the HVAC system causes higher energy bills. Regular home air filter replacements can prevent expensive system repairs or replacements down the road.

You should change your filter more frequently if you notice:

  • Household dust build-up
  • The air isn’t cooling as is used to
  • There’s more dust near the air vents
  • A dirty filter surface
  • Higher energy bills
  • Burning smells near your HVAC system.

20x21x1 Air Filter

Filter King 20x21x1 size air filters are used by your air systems to protect your home by cleaning out incoming airflow. Your air systems will constantly bring air inside, but there is no way for them to be able to tell the clean air from the dirty. Pleated air filters are installed so that all the air passing through has any traveling microscopic particles captured and absorbed in the tight mesh weaving. The process is necessary to keep your home’s indoor air quality up, but the air filters become dirty in the process. Dirty air filters are covered in airborne particles and present a clear problem for your home.

The pleated air filters in your home are necessary tools, but they become an issue when they become dirty. Dirty air filters become covered in the particles they have absorbed or captured, which makes it hard for air to pass through. When airflow has a problem making it into your home, the air inside is unable to cycle out leading to dryness and stagnation. Your air systems become strained as they try to push airflow through the blockage, resulting in mechanical damage and a rise in energy billing over time.

The pleated air filters in your home require regular maintenance to keep airflow coming in fresh and clean. We offer 20x21x1 size air filters at affordable prices that are usable upon arrival at your home. We also have a subscription option to have your orders delivered as often as monthly, orders of two or more pleated air filters are shipped out for free. Our air filters have a MERV rating (Minimum Efficiency Reporting Value) of eight, eleven, or thirteen and block particles like:

  • Pollen
  • Household Dust
  • Mold Spores
  • Dust Mites Mold
  • Lint Dust
  • Bacteria
  • Fine Dust
  • Pet Dander
  • Smoke
  • Viruses

20x21x1 Furnace Filters

The furnace filters in the system work as they do in any other home air system, cleaning airflow and keeping it clean before it enters your home. The pleated air filters will continue to clean out the heated airflow over time, but they become more and more dirty over time. Dirty furnace air filters block heated airflow, which leads to problems with temperatures over time. The furnace may become damaged and the air inside your home may face temperature fluctuations

We have in stock many filter sizes. Even if you have an HVAC unit that has an unusual filter size, you can order a custom size new filter with us. Purchase new filters today to help keep airflow coming in without issue.