Buying guide for best furnace filters
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Choosing a replacement furnace filter sounds pretty straightforward. But when I first needed one for my home, I quickly realized that, with so many sizes, MERV ratings, and brands to choose from, it's much more complicated than I thought.
If you deal with allergies or asthma, it can be even tougher to land on the right choice. Dust, pollen, pet dander and other particles floating around your home can make an already rough situation feel even worse. A good furnace filter can help trap some of those airborne irritants before they keep circulating through your home.
We researched the top furnace filters on the market to find the best options for different needs and budgets. Our favorite is the Filtrete Allergen Defense MERV 11, MPR 1000, 2-Pack.
Editors' picks
Filtrete Allergen Defense MERV 11, MPR 1000, 2-Pack
Editors’ Favorite
Dimensions: 20" W x 25" L x 1" H | MERV Rating: 11 | Material: Polypropylene
We love the Filtrete Allergen Defense MERV 11, MPR 1000, 2-Pack for its three-in-one technology that effectively traps allergens and dander. It’s one of the best filters for pet owners, and its 11 MERV rating makes it excellent at trapping microparticles in the air.
Only slightly more expensive than MERV 8 filters, these are designed for allergy sufferers. In some cases, they're a better option than MERV 13 filters because they don’t strain AC systems as much. Most users find it right in that sweet spot of filters for modern systems.
You can track your filter’s life in the Filtrete Smart App and set reminders up to 90 days in advance, so you always know when it’s time to change it.
FilterBuy MERV 8 Pleated Filter
Great Value
Dimensions: 19.50" W x 24.50" L x 3.63" D | MERV Rating: 8 | Materials: Aluminum, plastic, polypropylene | Special Features: Dust collection, easy to install, removable
The Filterbuy MERV 8 Air Filter's pleated design captures about 90% of dust particles while still allowing good airflow, which helps cut down on things like mold and pollen floating around your home.
Installation is simple thanks to the sturdy build and consistent sizing, though a few users have mentioned that the fit can be a little tight depending on the system. Compared to standard fiberglass filters, though, these hold up better and last longer.
All in all, it’s a reliable, cost-effective option if you want to improve your home’s air quality without overspending.
Filtrete Ultra Allergen AC Furnace Air Filter MERV 12
Best Long-Lasting Filter
Dimensions: 15.69" W x 24.69" L x 0.78" D | MERV Rating: 12 | Materials: Polypropylene
This Filtrete Ultra Allergen AC Furnace Air Filter is MERV 12 rated and effectively captures a wide range of microparticles, from pet dander to smoke, ensuring that cleaner air flows through. We appreciate its certification as asthma- and allergy-friendly, which adds a layer of reassurance for those concerned about allergens.
Plus, the Filtrete Smart App makes it a breeze to stay on top of filter changes, setting reminders for 30, 60 or 90 days. While some folks have found the fit a bit tricky, most agree it’s worth it for the air-quality improvement it brings.
Filtrete MERV 13 Filter MPR 1900
Best for Allergies
Dimensions: 15.44" W x 19.75" L x 4.31" H | MERV Rating: 13 | Material: Polypropylene
The Filtrete MPR 1900 is a noticeable step up from standard pleated filters. Its 3-in-1 filtration media, combined with a high MERV 13 rating, targets common contaminants like dust, pollen, and pet dander, along with finer particulates such as smoke.
It's also certified as asthma-and-allergy-friendly, which is huge if your household is focused on improving indoor air quality. The 4-inch pleated construction supports a longer service life compared to thinner filters, and these filters are sold in multi-packs, so you can stock up.
Some reviewers find the enhanced filtration worth the higher price point, but others prefer lower-MERV options for budget or airflow reasons. For households looking to improve indoor air quality with systems that can handle denser filters, this is a solid pick.
AprilAire 213 Replacement Filter
Best for AprilAire Systems
Dimensions: 20” x 25” x 4" H | MERV Rating: 13 | Material: Synthetic Fiber
A MERV 13 filter like the AprilAire 213 Replacement Filter is a good choice if your modern system can handle it. Made of synthetic fiber, it captures 15% more particles than leading brands, making it excellent for pet owners.
It can remove up to 97% of common allergens and 92% of viruses, making it a strong option if you live somewhere with harsh winters. The OEM design makes it perfect for AprilAire systems, and it doesn’t strain HVAC systems like other MERV 13 filters.
Unlike other filters, you don’t have to change this one often; it lasts about a year, compared to three months. It’s an industry-standard choice, especially for newer systems. That’s why we recommend it if you want clean air and fewer replacements over 12 months.
Trightfilters Air Filter 4-Pack, MERV 8 Filter Replacement
Best for Smaller HVAC Systems
Dimensions: 16" W x 20" L x 1" H | MERV Rating: 8 | Material: Aluminum, Polypropylene
Whether you have a small HVAC system or just want a cheap set of filters, the Trightfilters Air Filter 4-Pack, MERV 8 Filter Replacement is a great four-pack. For just $30, you’ll get four polypropylene filters that work very well with most HVAC systems.
These MERV 8 filters have more pleats than other brands, improving airflow and reducing strain on your system. They capture 92% of particles, including smoke, dander and allergens, so it’s also a good choice if you own pets like dogs or cats. Their construction is surprisingly solid for the price, and they hold up well over time.
It's easy to install and a terrific bargain pick for older systems. It works with furnaces, AC, HVAC and home vents, and its MERV 8 rating means lower resistance, which is great for small units.
Honeywell FC100A1029 Air Filter
Best for Honeywell or Lennox Cabinets
Dimensions: 16" W x 25" L x 4" H | MERV Rating: 11 | Material: Carbon Fiber
For homeowners or renters with a Bryant or Honeywell furnace/AC system, we recommend the Honeywell FC100A1029 Air Filter for your next replacement. These are exact OEM filters, so they're designed to work perfectly with most HVAC systems.
They have a MERV 11 rating, a great middle ground for anyone who wants more efficient filtering throughout their home. Deep accordion pleating means significantly less air restriction, especially when compared to MERV 13 filters. They can also last up to 12 months, which is three to six months longer than standard filters.
It’s a two-pack, so each filter costs around $30, which is a fairly good deal for an original Honeywell filter. You’re getting a certified filter, so you can rest assured performance will hold up as it has for so many customers.
NordicPure MERV 12 Pleated AC and Furnace Air Filters
Best for Enhanced Filtration
Dimensions: 16" W x 25" L x 1" H | MERV Rating: 12 | Material: Electrostatically Charged Synthetic Pleated Media
Although the NordicPure MERV 12 Pleated AC and Furnace Air Filters are cheaper than some of our other picks, they’re actually surprisingly effective at trapping particles. They’re a great budget pick, especially if you want a handful of replacements for the next two years or so.
The pack includes six filters, each made of electrostatically charged, pleated synthetic media. The MERV 12 rating makes them nearly as effective as MERV 13 filters, but they’re noticeably easier on modern systems. They’re great at removing dust and pollutants without straining your blower motor, and they capture super-fine particles to keep the air clean.
They don’t last as long as some of our top MERV 13 or even MERV 11 picks, but their low price means you can replace them often for about the same cost as more expensive filters.
Aerostar MERV 11 Pleated Air Filter, 12-Pack
Best for Stocking Up
Dimensions: 16" W x 25" L x 1" H | MERV Rating: 11 | Material: Synthetic
You won’t find a better value pick than the Aerostar MERV 11 Pleated Air Filter, 12-Pack, especially if you’re stocking up for the next two or three winters. This 12-pack of filters is a great choice for nearly any HVAC system thanks to its MERV 11 rating.
These filters capture dust, pollen, pet dander, mold, smoke and smog in your home AC and furnace, directly affecting your home's air quality. That means they make life at home much more manageable for asthma sufferers and pet owners. They also retain their shape well after 90 days of consistent airflow, making them longer-lasting than standard budget filters.
They’re surprisingly durable for a cheaper option, so we don’t see any noticeable durability concerns. They work well in most HVAC systems and furnaces and perform significantly better than fiberglass filters.
Why changing your furnace filter is important
A filter might seem like a fairly insignificant part of a furnace or A/C system, yet good airflow is vital. If your filter is clean, your system works efficiently. If it's clogged and dirty, your system works harder than it should. That means higher bills and lower air quality.
Some suggest that a little dust is no bad thing, that it can actually improve filtration. That's not really an accurate reflection of what's going on. Less-efficient filters get more efficient as they load since the pores begin to fill and spaces between the media fibers get smaller, and they start trapping finer dust. However, this “advantage” is short-lived. The filters continue to clog quickly, and the dust soon dramatically restricts airflow.
Expert tip
To be sure you are inserting your filter the right direction, use a marker to draw an arrow on the unit after confirming with the manual. Now, you won’t inadvertently install it backward.
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The best solution is a proper maintenance schedule. It's a good idea to keep a log, check your filter regularly, and replace it as recommended by the manufacturer (or if you notice its performance starting to deteriorate).
It's false economy to try to extend the life of filters beyond their specifications. Any money you might save on the filters themselves is lost on higher energy bills. If anyone in the household has respiratory difficulties, you're also making things tougher on them.
How a furnace filter is made
Filters usually have an aluminum, a steel, or a plastic framework containing a filtering element made of fiberglass, polyester, cotton, or paper. They're designed to trap particles of dust and dirt that adversely affect the components and performance of your system and have a negative impact on household air quality.
The majority of filters are pleated, offering a large surface area without increasing the exterior dimensions.
Filters can be disposable or washable. Disposable filters are convenient, easy to change, and usually last several months. Washable filters can last years if looked after properly. But they must be cleaned regularly (usually every 30 days) and thoroughly. If not done correctly, there is a danger of spreading bacteria.
For your safety
Most furnace filters have a front and back. It's important you fit yours the right way, or airflow will be compromised. Instructions will be provided, so read carefully. Often, there's also an arrow on the side indicating the correct direction.
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Choosing the right furnace filter
There are two things to check when choosing a replacement furnace filter: size and filtration level.
Size
It's important to get the right size, as there's no room for maneuvering. Furnace filters either fit or they don't.
Sizing should be clear from your existing filter and will be given as the width x height x thickness –16 x 25 x 1, for example. These measurements are in inches, but the inch marking is not normally shown.
Most filters are one inch thick, but some are two or even four inches thick. In theory, a thicker filter gives greater filtration – but they aren't interchangeable. If your existing filter is one-inch thick, a four-inch filter isn't going to fit without serious modifications to your system. Even if that were practical (which is unlikely), your system likely only has sufficient airflow for a one-inch filter anyway. Putting in a thicker version would actually reduce effectiveness.
Filtration level
HVAC systems and filters are a lot like vacuum cleaners; they should move enough air to clean the environment without allowing the dust to blow back into your home. The vast majority of disposable furnace filters are rated according to the MERV scale created by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers. The higher the number, the finer the filter, so the more particles it traps.
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Disposable filters offered for household use vary between MERV 6 and MERV 12. However, experts recommend MERV 8 as a minimum and MERV 10 or 11 for better odor control.
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Commercial filters are available with much higher MERV ratings, but most household systems don't generate sufficient airflow, so they should not be used.
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Washable filters are not covered by MERV ratings, and their specifications can seem confusing. Some claim to trap a certain percentage of airborne particles, but they don't tell you what size those particles are.
However, manufacturers' claims such as “removes 95% of dust” are meaningless without knowing the size and type of particles. A very poor (airy) filter can trap 95% of larger particles, but only 3% of very small particles. Some filters that claim to remove 99% of pollen or mold are basing that on removing whole pollen or mold grains and do not factor in particle fragments, since pollen and mold can break up into finer particles.
Expert tip
Set your Google Calendar, Alexa, or Siri device to remind you to replace filters every three months.
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Electrostatic furnace filters
Many furnace filter manufacturers now use the expression "electrostatic" in their product descriptions. An electrostatically charged filter is better than a standard pleated filter with many contaminants, and they’re recommended for homes with allergy sufferers, smokers, or pets. The electrostatic charge is added during manufacturing. There is no requirement for a separate electrical supply. It's not something that needs to be re-charged.
Furnace filter prices
A good furnace filter isn't expensive. However, it is difficult to give accurate prices because of the enormous variety of materials and sizes and the competitive nature of the available furnace filters.
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As a rough guide, disposable furnace filters start at around $7 or $8 each for 20 x 20 x 1. The price rises to between $15 and $20 for 20 x 30 x 4. MERV rating has little impact.
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Washable filters, not surprisingly, are considerably more expensive. Expect to spend anywhere from $30 to $50 each, depending on construction.
Caution
Never run your furnace or HVAC system without the proper filter. Not only will it adversely affect your air quality, it will also allow dirt and dust into parts of the system that should remain uncontaminated. The result will be poor performance, higher bills and breakdowns.
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How we analyzed
We considered filters with varying MERV ratings to give homeowners and renters more flexibility in choosing the right filter. We included lower-rated MERV filters for smaller or older systems, and higher ratings for modern systems built to withstand more airflow. We also considered material and longevity, since some filters naturally last longer than others.
Tips
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Check the specs: Filter quality and worth depend on the application, including the size and airflow of the HVAC system. For example, the higher the MERV filter number, the better the dust removal — if your system can push air through it.
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Keep your air clean: Running the HVAC system on a continuous fan is the best way to clean the air regardless of the type of filter you use.
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Efficiency matters: Less-efficient filters get more efficient as they load since the pores begin to fill, spaces between the media fibers get smaller and they start trapping finer dust. Of course, this also means the filters are clogging and will soon obstruct airflow.
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Know when to change the filter: How often you need to change the filter will depend on how efficient it is, how much you run the fan on your HVAC unit and how many dust sources you have inside.
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Choose the best: The best filters tell you the percentage of particles removed by size at a given airflow.
FAQ
Q. What is a micron?
A. A micron (or micrometer) is one-millionth of a meter or 0.000039 inch. To give you an idea of just how small that is, a human hair is about 70 microns thick.
Expert tip
To support better filtration, vacuum your return vents monthly to minimize dust in your HVAC system and ultimately your filter.
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Q. What is the purpose of a HEPA filter, and are they the best?
A. HEPA (high-efficiency particulate air) filters are extraordinarily efficient, removing nearly 100% of particles as small as 0.3 microns. However, they have a very dense structure, and most furnaces don't produce sufficient pressure to drive air through them. If that's the case, all you're doing is blocking up your system and actually getting no filtration at all.
A great filter is the most efficient one your HVAC system can handle while still moving enough air to make a difference.
Q. How often do I need to replace my furnace filter?
A. It depends on a variety of factors. Standard, one-inch-thick filters should be changed after around 90 days, but thicker filters can last much longer.
If you have pets or are a smoker, your filters will become clogged more quickly. If you have breathing difficulties, you'll probably want to change them more often because you'll be more susceptible to airborne particles.
Your furnace or HVAC manual should give you the information you need. You can also get information from filter suppliers. Follow the instructions carefully.
