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Published Oct. 1, 2021

The HVAC system is responsible for heating and cooling your home, but it can’t function properly without a working furnace to heat the air and blow it through the ventilation system. A clean furnace filter is necessary to help prevent the furnace from overheating and keep it efficiently trapping airborne particles, allergens, and pollutants.

Furnace filters can be either disposable or reusable, if you don’t mind washing it when it becomes clogged, and they range in both size and thickness. Different furnaces require specific filters, so the best furnace filter for your home depends on the make and model of the furnace. Check the user’s manual and also inspect the old furnace filter to find the appropriate size and thickness before taking a look at this list of top products. Then keep reading for a better understanding of the various furnace filter types, sizes, thickness, and MERV ratings.

How We Picked the Best Furnace Filters

Methodology

Almost every house has a furnace that needs regular maintenance that includes replacing the furnace filter, so it was a simple matter to apply firsthand experience to the selection of these top products from over 40 different options. Extensive research was also necessary to ensure that each product was thoroughly reviewed before the best furnace filters were chosen. Careful consideration was given to the MERV rating, size, thickness, and furnace filter type as well as any extra features that the filter had to offer. 

Preference was given to products with high-efficiency ratings, though this was balanced against the overall price and value of each furnace filter product. The MERV rating of each furnace filter was a key factor given that this is a direct measure of the product’s filtration capabilities. Any specific mention of specialized uses, such as pet dander control or allergen filtration, was also taken into account when deciding between two or more similar products.

The Best Furnace Filter: Reviews and Recommendations

Best Overall: Nordic Pure 16x16x1 MERV 12 Pleated AC & Furnace Filter

High-Efficiency Electrostatic Filter

Improve the air quality of the home by replacing an old, used furnace filter with this high-efficiency option. Nordic Pure

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Why It Made the Cut: With a MERV rating of 12, this Nordic Pure furnace filter is one of the most effective filtration options for a residential HVAC system.

Specs: 

  • Type: Electrostatic furnace filter
  • Size: 16 x 16 x 1 inches
  • MERV Rating: 12

Pros:

  • High efficiency
  • Six filters in one pack
  • Ideal for trapping allergens
  • Affordable

Cons:

  • Must replace every one to three months

This six-pack of Nordic Pure 16x16x1 MERV 12 Pleated AC & Furnace Filters is an excellent option to keep the home HVAC system operating at high efficiency for up to a year and a half. Simply replace the old furnace filter a minimum of once every three months to keep the air clean and avoid putting unnecessary stress on the heating and cooling system. The electrostatic construction is specifically designed to attract and trap airborne particles, making it easier for this filter to block the movement of allergens through the furnace. 

This filter has nominal dimensions of 16 by 16 by 1 inches, but the actual dimensions are 15.75 by 15.75 by 0.75 inches, so users need to make sure to properly measure the old furnace filter to ensure a proper. As long as the furnace filter is compatible with the furnace, users can enjoy the high efficiency of this MERV 12 product, though it should be noted that the filter may need to be changed monthly in homes with many pets, as the filter will become clogged at a faster rate.

Best Value: Aerostar 16x25x1 MERV 11 Pleated Air Filter

Filters Pet Dander

Keep the air clean with this furnace filter specifically designed for trapping pet hair, pet dander, and other allergens. Aerostar

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Why It Made the Cut: Users can update their existing filter with a high-efficiency product from Aerostar that has an impressive MERV rating of 11.

Specs: 

  • Type: Electrostatic furnace filter
  • Size: 16 x 25 x 1 inches
  • MERV Rating: 11

Pros:

  • High efficiency
  • Suitable for trapping a wide range of airborne pollutants
  • Inexpensive six-pack

Cons:

  • Must be replaced every two to three months

If you  have pets or are just looking for an affordable value, this six-pack of Aerostar 16x25x1 MERV 11 Pleated Air Filters is a great choice. Each filter boasts a MERV rating of 11, which is impressive for a product made to be used in residential furnaces. The filters have nominal dimensions of 16 by 25by 1 inches and actual dimensions of 15.75 by 24.75 by 0.75 inches. Unfortunately, the thinness of these filters means that they do need to be replaced about once every two to three months. The synthetic electrostatic fiber attracts and traps microscopic particles such as lint, dust mites, pollen, smoke, dust, and pet dander, reducing your exposure to airborne irritants, pollutants, and allergens. These filters are also helpful in preventing mold by trapping spores before they can be blown through the HVAC system and into the home.

Best Allergen Protection: AIRx Allergy 20x20x1 MERV 11 Pleated Air Filter

Trap Airborne Allergens

Use this high-efficiency furnace filters to trap and remove irritants and allergens. AIRX FILTERS WICKED CLEAN AIR.

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Why It Made the Cut: Lint, dust, dust mites, pollen, mold, smog, pet dander, pet smells, and even bacteria can be trapped by this MERV 11 pleated fiberglass furnace filter.

Specs: 

  • Type: Pleated fiberglass furnace filter
  • Size: 20 by 20 by 1 inches
  • MERV Rating: 11

Pros:

  • High-efficiency MERV rating of 11
  • Designed for trapping allergens such as pollen, dander, and other debris
  • Affordable value pack

Cons:

  • Filter must be changed every two to three months
  • Not effective for filtering smoke or viruses

The AIRx Allergy 20x20x1 MERV 11 Pleated Air Filter is a suitable choice for users with allergies or who may have a hard time breathing in musty locations. This is a six-pack of filters with an impressive MERV rating of 11, ensuring that they can trap a wide range of airborne pollutants. Specifically, these pleated fiberglass furnace filters are made for eliminating allergens from the home, so they are capable of trapping lint, dust, dust mites, pollen, mold, smog, pet dander, pet smells, and bacteria. However, it should be noted that these filters cannot trap smoke particles or viruses. 

Each furnace filter has nominal dimensions of 20 by 20 by 1 inches and actual dimensions of 19.5 by 19.5 by 0.75 inches. It’s important to change the filters once every two to three months because they tend to get clogged quickly.

Best Odor Neutralizer: Flanders NaturalAire Odor Eliminator Filter

Remove Noxious Odors

These baking soda-infused furnace filters absorb and eliminate unpleasant odors. Flanders

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Why It Made the Cut: This odor-neutralizing furnace filter takes care of pet odors and the lingering scent of smoke.

Specs: 

  • Type: Pleated fiberglass furnace filter
  • Size: 20 x 20 x 1 inches
  • MERV Rating: 8

Pros:

  • Baking soda-infused to eliminate odors
  • Four-pack lasts up to 12 months
  • Suitable for trapping dust, pollen, dirt, and mold spores

Cons:

  • Modest MERV rating of 8

Invest in this affordable four-pack of furnace filters to ensure that your furnace and HVAC system remain in good working order for up to 12 months. Replace the old furnace filter every two to three months to keep the air clean and odor-free. These filters physically trap dust, pollen, dirt, mold spores, and other airborne contaminants. But their real benefit is that they can neutralize offensive odors as they pass through the HVAC system using the odor-absorption quality of baking soda. 

The filters measure 20 by 20 by 1 inches, but they have a MERV rating of only 8. While this isn’t the lowest MERV rating available, the efficiency of these filters can be said to be modest. 

Best Smart Filter: Filtrete 12x12x1 Smart Air Filter

Automatic Replacement Notifications

Automatically know when the furnace filter needs to be changed with this smart filter. Filtrete

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Why It Made the Cut: The free Filtrete app connects wirelessly to a chip installed on the furnace filter to track airflow, usage, and filter life.

Specs: 

  • Type: Electrostatic furnace filter
  • Size: 12 x 12 x 1 inches
  • MERV Rating: 12

Pros:

  • Convenient Bluetooth connection
  • High efficiency
  • Traps allergens, bacteria, and even viruses

Cons:

  • High price
  • New reporting technology

The Filtrete 12x12x1 Smart Air Filter is designed with a chip that measures airflow, filter usage, and filter life. The chip connects wirelessly via Bluetooth to the Filtrete app, allowing users to check the status of the furnace filter at any time instead of trying to estimate when the filter should be changed. The filter comes at a higher price than standard furnace filters and uses relatively new technology, and it should be noted that there may be some bugs that still need to be worked out as the reporting technology is perfected.

The pack includes two electrostatic filters with nominal dimensions of 12 by 12 by 1 inches and actual dimensions of 11.84 by 11.84 by 1 inches. These filters have a MERV rating of 12 and are capable of trapping a wide variety of airborne pollutants, including dust, pollen, dander, mold spores, smoke, bacteria, viruses, and other debris. 

Things to Consider Before Buying a Furnace Filter

A furnace filter is a necessary part of the furnace that must be replaced regularly to prevent premature wear and tear on the HVAC system. However, before choosing a furnace filter it’s important to understand the various filter types, sizes, and MERV ratings in order to find the best furnace filter for your home.

Furnace Filter Types

Finding the right furnace filter can save you money, improve your home’s air quality, and reduce wear and tear on your HVAC system, so it’s necessary to have an understanding of the various filter types, which include fiberglass, polyester, cotton, electrostatic, and HEPA. 

  • Fiberglass furnace filters are the most basic option available, usually with a 1-inch thickness and a low MERV rating of just 2 to 3. While these filters are low on cost, they have little effect on air filtration and need to be changed frequently. However, pleated fiberglass furnace filters have a significantly increased efficiency that can reach a MERV rating between 8 and 11.  
  • Polyester furnace filters come in flat and pleated versions with an average MERV rating that falls between 6 and 8. They are better than fiberglass and relatively inexpensive. Also, the thickness of polyester filters can range from one to five inches, allowing them to be used for a longer period before needing to be replaced. 
  • Cotton furnace filters can also be called high-efficiency pleated filters and they are usually four to five inches thick. These filters have a high MERV rating between 14 and 16 and are even suitable for hospital use, though cotton furnace filters cost more than either fiberglass or polyester. 
  • Electrostatic furnace filters are also typically made with cotton, though they can sometimes be made with paper fibers as well. What sets these furnace filters apart is that the material is self-charging, meaning that it automatically generates a static charge in order to attract small particles and improve filtration. They tend to be thinner than high-efficiency cotton filters and have a MERV rating of about 10. 
  • HEPA (high-efficiency particulate air) furnace filters are the most impressive options available, with MERV ratings that usually fall between 16 and 20. They are capable of trapping up to 99.7 percent of airborne pollutants, but these filters are not commonly made for residential furnaces, so they may be hard to find in the correct size.

Also, keep in mind that there are disposable furnace filters and reusable filters. So, if you don’t mind scrubbing the filter every few months, it may be more cost-effective to invest in a reusable filter.

Size and Thickness

The size of the furnace filter is a key measurement that you need to know before you can find a replacement filter. Keep in mind that furnace filters come in a wide range of sizes, so check the size of your current furnace filter so that you know exactly what size you need. Also, a filter’s actual dimensions may differ from its nominal dimensions, so be sure to carefully confirm both your existing furnace filter’s measurements and those of any replacement filter.

The thickness of the filter is another important measurement. In general, the thicker the filter the less often it will need to be changed; however, thicker filters can also be more difficult to push air through and can cause overheating if the HVAC system is not meant to work with them. This is why you need to consult the user’s manual to see whether thicker filters can be used in your system without negatively impacting the functionality.

MERV Rating

To better understand the capabilities of an individual furnace filter, check the MERV rating. MERV stands for Minimum Efficiency Reporting Value and basically refers to the ability of the filter to trap airborne particles and pollutants. The MERV scale ranges from low-efficiency fiberglass filters with MERV ratings between 1 and 3 to high-efficiency HEPA filters with MERV ratings ranging from 16 to 20.

The typical MERV rating for a residential furnace filter falls between 6 and 12. It should be noted that the more efficient the filter, the more often it should be changed, as high-efficiency filters tend to clog faster than less efficient products.

FAQs

How often should furnace filters be changed?

It’s important to replace the furnace filter regularly in order to prevent problems with the HVAC system. On average, filters should be replaced every 3 to 12 months, depending on the thickness of the filter. A one-to-two-inch-thick filter should be replaced about once every 3 months; those that are three- to four inches thick should be replaced once every 6 to 9 months; and filters with a thickness of five to six inches should be replaced once every 9 to 12 months.

What happens if you don’t change your furnace filter?

Furnace filters are an important part of the HVAC system that help to trap dust, dirt, hair, allergens, and other debris. However, when the furnace filter becomes partially or fully clogged with debris, it limits the flow of air, causing the furnace to operate for a longer period in order to increase or decrease the temperature in the home. This increased operation puts strain on the system and can cause the furnace to overheat and wear out quickly, which is why it’s necessary to regularly change the furnace filter.

Can a dirty furnace filter make you sick?

The purpose of a furnace filter is to trap airborne pollutants such as dust, dirt, hair, and other debris. If the filter becomes clogged, its ability to do so is severely limited, leading to a potential increase of allergens in the air. A clogged filter can also contribute to mold growth within the system. While a dirty filter does not directly affect your health, the unfiltered pollutants, allergens, and mold can cause your body to react negatively and may lead to illness.

Final Thoughts

A furnace filter may not be top of mind, but keeping yours in good working condition will improve the quality of the air you breathe every day. Keep the air in your home fresh and allergen-free with the Nordic Pure 16x16x1 MERV 12 Pleated AC & Furnace Filter, our pick for best overall furnace filter. Pet owners may prefer our value pick, the Aerostar 16x25x1 MERV 11 Pleated AirFilter, which is specifically made to trap pet dander and other allergens.

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