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Your HVAC system is responsible for heating and cooling your home, but it can’t function properly without a working furnace with a fresh furnace filter to heat the air and blow it cleanly through the ventilation system. A furnace filter is necessary to help prevent the furnace from overheating and keep it efficiently trapping airborne particles, allergens, and pollutants. Filters can be either disposable or reusable (if you don’t mind washing them when they become clogged), and they range in size and thickness. Different furnaces require specific filters, so the furnace filter for your home depends on the make and model of the furnace. Check the user’s manual and 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 to understand better the various types, sizes, thickness, and MERV (Minimum Efficiency Reporting Value) ratings of the best furnace filters.

How we chose the best furnace filters

Many homes have a furnace that needs regular maintenance, including replacing the furnace filter. I applied first-hand experience to selecting these top products from over 40 options. I conducted extensive research, including carefully considering the MERV rating, size, thickness, furnace filter type, and any extra features the filter had to offer.

The best furnace filters: Reviews & Recommendations

I preferred filters with high-efficiency ratings for these selections, 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. I also weighed specialized uses, such as pet dander control or allergen filtration, when deciding between two or more similar products.

Best overall: Nordic Pure MERV 12 Pleated AC Furnace Filter

Nordic Pure


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.


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


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


  • 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 efficiently 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, so users need to measure the old furnace filter to ensure a proper fit. As long as the furnace filter is compatible with the furnace, users can enjoy the high efficiency of this MERV 12 product. However, it should be noted that the filter may need to be changed monthly in homes with many pets, as it will become clogged faster.

Best for allergies: AIRx Allergy MERV 11 Pleated Air Filters



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.


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


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


  • 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 suitable for users with allergies or who may have difficulty breathing in musty locations. This is a six-pack of filters with an impressive MERV rating of 11, ensuring they can trap a wide range of airborne pollutants. Specifically, these pleated fiberglass filters are made to eliminate allergens from the home, so they can trap 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. Changing the filters once every two to three months is important because they tend to get clogged quickly.

Best odor neutralizer: Flanders NaturalAire Odor Eliminator Filter



Why it made the cut: This odor-neutralizing furnace filter takes care of pet odors and the lingering scent of smoke.


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


  • Baking soda-infused to eliminate odors
  • 12-pack lasts a long time
  • Suitable for trapping dust, pollen, dirt, and mold spores


  • Modest MERV rating of 8

Invest in this affordable 12-pack of filters to ensure 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 have a MERV rating of only 8. While this isn’t the lowest MERV rating available, the efficiency of these filters is modest.

Best smart: Filtrete Smart Air Filter



Why it made the cut: The Filtrete app connects wirelessly to a chip installed on the furnace filter to track airflow, usage, and filter life.


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


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


  • 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 more expensive than standard furnace filters and uses relatively new technology. It should be noted that some bugs may 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 can trap various airborne pollutants, including dust, pollen, dander, mold spores, smoke, bacteria, viruses, and other debris.

Best budget: Aerostar MERV 11 Pleated Air Filter



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.


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


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


  • Must be replaced every two to three months

If you have pets or are just looking for an affordable option, 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 25 by 1 inches, and actual dimensions of 15.75 by 24.75 by 0.75 inches. Unfortunately, the thinness of these filters means they 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 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.

Things to consider when buying a furnace filter

A furnace filter, along with an HVAC 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 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 in cost, they have little effect on air filtration and must be changed frequently. However, pleated fiberglass 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 of 6 to 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 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. What sets these filters apart is that the material is self-charging, which automatically generates a static charge 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, with MERV ratings usually falling between 16 and 20. They can trap up to 99.7% 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 filters and reusable filters. So, if you don’t mind scrubbing the filter every few months, investing in a reusable filter may be more cost-effective.

Size and thickness

The size of the furnace filter is a key measurement you need to know before finding a replacement filter. Keep in mind that 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 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.


Q: How often should furnace filters be changed?

It’s important to replace the furnace filter regularly 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 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.

Q: 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 to increase or decrease the temperature in the home. This increased operation strains the system and can cause the furnace to overheat and wear out quickly, so it’s necessary to change the furnace filter regularly.

Q: 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 on the best furnace filters

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

Why trust us

Popular Science started writing about technology more than 150 years ago. There was no such thing as “gadget writing” when we published our first issue in 1872, but if there was, our mission to demystify the world of innovation for everyday readers means we would have been all over it. Here in the present, PopSci is fully committed to helping readers navigate the increasingly intimidating array of devices on the market right now.

Our writers and editors have combined decades of experience covering and reviewing consumer electronics. We each have our own obsessive specialties—from high-end audio to video games to cameras and beyond—but when we’re reviewing devices outside of our immediate wheelhouses, we do our best to seek out trustworthy voices and opinions to help guide people to the very best recommendations. We know we don’t know everything, but we’re excited to live through the analysis paralysis that internet shopping can spur so readers don’t have to.