How to Choose a Furnace Filter

The maintenance of furnace filters is an essential task for any building’s HVAC system. Furnace filters can remove all the harmful particles that might be in the air, but they need to be replaced regularly in order to work properly. If you suffer from asthma or allergies, furnace filters should be a top priority. However, the sheer number of options for furnace filters out there can be overwhelming when you begin shopping. For some guidance, please read these tips on how to choose a furnace filter that is perfect for your situation.

Determine the Size

The first part of our guide on how to choose a furnace filter is to determine the size you need for your home. The most common-sized filters are 16″ x 20″, 20″ x 25″, and 16″ x 25.” Nonetheless, there are still plenty of other sizes available at, including a customization option if you don’t see the size you need. The size is essential because your filter must fit properly into the cabinet so air doesn’t escape through any open cracks.

Its Purpose

Another factor to keep in mind when looking for a new furnace filter is the purpose it will serve. More specifically, are you getting a filter for commercial, residential, industrial, or high-efficiency particulate air (HEPA) reasons? Keep the environment in mind when you are looking a filter because this might affect the type and quantity you will purchase.

Consider the Different Types

Like we previously mentioned, there are many different types furnace filters you can get that each work in a very specific way:

  • Pleated filters are made out of polyester, cotton, or paper. The filters are also pleated and can cover the entire surface area, so it can stop particles in the air like dirt, dust, and hair from damaging the blower’s fan or cause clogged AC coils.
  • Basic filters are also an effective option to combat all the different particles that could disrupt your HVAC system.
  • Washable filters, also known as electrostatic filters, are a great option if you want to reuse them. While washable filters are good at keeping out dust, they aren’t as effective when it comes to hair, viruses, smoke, and other small airborne particles. To clean a washable filter, all you need to do is use a vacuum, a brush, soap, and water to remove any particles that might be on it. It’s recommended that you clean the filter by checking to see if any light passes through. If there isn’t any light passing through, then it’s time to wash the filter.
  • Fiberglass filters are another great option for catching large particles like dust, lint, and other debris.
  • Exact fit is a filter from both and AAF Flanders. With over 70,000 filter sizes available, you can find the right filter size that you need in the different forms previously mentioned.
  • Grille cut is another option you can go with if you are looking to replace your filter. One thing to note is that the largest dimension will be listed first and will typically be 7/8” smaller than what is actually printed on the filter. Additionally, the short size will probably be 5/8” smaller. While they might be difficult to find elsewhere, has plenty in stock.
  • There are some instances where you might need a mechanical HEPA filter. If this is the case, we can give you a quote on a part number and get the right build.

Keep these different types of filters in mind when looking for a new air filter for your furnace system. has all of the above filter types and more available for you.

Brand Name

Filters are produced by a number of reputable companies. This is yet another way you can search for your filters. If you’ve had success with a brand in the past, you can stick with them, or if a certain brand did not work out for you, you can try another. has the following brands that you can choose from:

  • AAF Flanders is a manufacturing leader and continues to produce clean air for major organizations. High-quality AAF Flanders filters are used by NASA, among other organizations, and in many hospitals as well as residential, commercial, and industrial properties.
  • NaturalAire provides filters that are great for both furnaces and HVAC systems. NaturalAire, produced by AAF Flanders, are comprised of one-sided metal—reinforced pleated media.
  • EZ Flow offers a line of filters that are used for industrial equipment and residential protection. For light industrial equipment, these filters can play a big role in lowering energy bills by keeping cooling and heating coils clean.

MERV Ratings

Each filter is also assigned a Minimum Efficiency Reporting Value (MERV) rating. A MERV rating will essentially tell you how effective an air filter is, with a rating from 1-16. A MERV rating of 7-12 is typical for residential buildings, while a MERV ratings of 13-16 is appropriate for hospitals. A MERV rating indicates how effective the product can be, based on the setting that’s used, which is why it needs to be on the top of your checklist.


When choosing a furnace filter, you also need to keep in mind its longevity. While different kinds of filters vary in terms of longevity, they should typically be replaced every 3 to 6 months. With that in mind, think about buying filters for a year so you can easily replace them. However, we still recommend that you check your filter every now and then, or at least keep track of when you have been replacing them.


A final factor that plays into the selection of a filter is the price of the filter itself. There are a variety of elements that play into the price of a filter, such as quality, for example, but you can find what works best for your budget with filter packs ranging from $40 to $200 for 12, which can last you several years.

How to Choose a Furnace Filter

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