The Best Furnace Filter to Buy - The Definitive Furnace Filter Guide

The Best Furnace Filter to Buy - The Definitive Furnace Filter Guide

Figuring out the best furnace filter to buy can be difficult.  After all, the best filters can range widely in both price and features, but which of those features are important?  Well, as with most things in life, it depends…are you interested in the best furnace filter for allergies, or just for general use?  In this article, we’ll break it down.  Those of you who have read our articles, know that we are a small, U.S. Veteran-Owned HVAC company located in California, and pride ourselves on giving our customers straight answers – this will be no different.  This guide to buying a new furnace filter will start by defining our terms, so we are all on the same page, then we’ll discuss the best furnace filters to buy for general use, and finally, we will address special needs such as furnace filters that can reduce allergies and asthma symptoms.

The Best Furnace Filter to Buy – A Definition of Terms


Best Furnace Filters - 3m

Ok, I am nerding-out a bit, I know.  But, when we start throwing around terms like the best furnace filter, what exactly are we talking about?  After all, your opinion of “best” is going to vary widely from mine.  Here’s Amazon’s take: The Best Furnace Filters, based solely on the number of units sold.  So, in this section, we will revert to Lincoln-Douglas Debate logic, and define our terms (nerd joke).  In short, for those of you who are impatient, today’s definition of the best furnace filter will be defined as such:

  1. It will be defined as the furnace filter that provides the best protection for your furnace’s internal components.
  2. The best furnace filter will provide a trade-off; we are interested in a filter that also provides adequate airflow to your furnace (more on this later).
  3. We will only be addressing disposable furnace filters in today’s article.  Expensive electro-static filters and UV purifiers will NOT be addressed.  In fact, disposable filters are the best, and your furnace filter should be changed every three months, for proper operation of your furnace.  For more on why that is, try:

Factors NOT considered for the purposes of defining the best furnace filter include:

  1. Cost – the most expensive disposable furnace filter is around $25.00, and the cheapest is $0.50.  Because this falls within the realm of affordability to the average consumer, we will NOT be rating furnace filters based on price today.
  2. Special needs (asthma and allergies) will be addressed at the end of this article, but will not be factored into our general use discussion of the best furnace filters.

Why We Have to Define the “Best Furnace Filter

From a technical standpoint, when discussing the best furnace filter for your system, it is important to understand how your furnace works at a very basic level.  Although an in-depth look at furnace performance and features is outside the scope of this article, it is important to realize two things:

First, the purpose of a furnace filter is NOT to improve your indoor air quality, believe it or not.  The purpose of your furnace’s filter is actually to keep dust and debris in the air from collecting on the inside of your furnace’s internal components, specifically the heat exchanger (the tubes that get hot and actually heat your air).  Imagine, for a moment, that we didn’t do this…have you ever seen a table that hasn’t been dusted in five or ten years?  Now imagine that the inside of your furnace was circulating air for five or ten years without proper filtration – that’s a lot of dust.  As such, your furnace filter keeps the air that your furnace ingests clean, preventing such buildup.  Cheap filters – typically fiberglass filters that you can see through, and even poke your finger through – don’t trap enough dust, which in turn, causes the buildup of dust on your heat exchanger.  This causes a burning smell in your house every time you turn it on (less than desirable), and can reduce the lifespan of your furnace.

The second part is equally important – if your furnace filter is “too good,” it blocks everything from passing through, even some of the air flow!  So, the best furnace filter should also be able to allow adequate air flow to your furnace, and not block air from getting to your blower motor (the fan that circulates air throughout your house).  For more on how to properly change your furnace filter, try this article: Consumer Reports – How to Replace Furnace Filters.

How Are Furnace Filters Measured?  MERV vs. MPR

So, before we move on with our discussion of the best furnace filters, let’s talk about how filters are measured.  There are three methods for measuring the filtration capacity of a furnace filter: MERV, MPR, and FPR.  In today’s discussion, we will skip the latter, and focus on the first two (the third method – FPR – was invented by The Home Depot, so who cares?).

MERV Furnace Filter Rating

MERV stands for Minimum Efficiency Reporting Value, and is regulated by the American Society of Heating, Refrigeration and Air Conditioning Engineers, aka “ASHRAE.”  If you’ve never heard of ASHRAE, then let me tell you…you haven’t lived!  Actually, to be honest, I was in this business for years before I heard of them, so don’t go flogging yourself just yet.

Random tangent – actually, I always found the name “MERV” funny…I guess it comes from my background in strategic defense as a Naval Aviator.  Where I come from, a MIRV (spelled differently, but pronounced the same) is a Multiple Independently Targetable Reentry Vehicle – basically a big ICBM nuke with multiple warheads on the end of it.  Yay mankind…

For those of you with a sense of humor, here is a brief movie scene that discusses what I think of, when I hear the word “MERV.”  If you don’t have a sense of humor that you are aware of, please feel free to skip it – it has nothing to do with this article:

…I digress…and as my wife is so fond of telling me, “stay on topic.”

Back on topic – in regards to discussing the best furnace filter for your home, the MERV rating is a numeric range from 1-16, with a higher MERV rating meaning that the filter is capable of filtering out more particles in the 0.3 to 1.0 micron range.  Translation: the higher the MERV number, the better the filter is at filtering.  Below, is a chart giving the basic description of the MERV standard of evaluating the best furnace filter.  But, filtration isn’t everything, so don’t go buying just yet there, sparky.

The best furnace filter - MERV rating.

MERV Filtration Chart – Click to Enlarge.

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MPR Furnace Filter Rating

The MPR method, or Microparticle Performance Rating, is a proprietary method for evaluating the best furnace filter.  It was created by 3M Furnace Filters, and only 3M Filtrete (company product name) products display it.  Many people like to site this as a negative, but in my experience, both in the military, as well as an independent contractor, the private sector always makes the best stuff.  Plus, 3M products are absolutely top-notch.

The 3M, MPR filter rating method has a range from around 300 MPR to 2800 MPR, with the higher number providing more filtration power.  I’ll be frank…3M makes the best products, in our not-so-humble opinion.  Plus, all 3M products also display the federal MERV rating, so it’s like two for the price of one!  Actually, they are expensive, as far as filters go, so it is more like two for the price of two.

Below is a chart depicting the various Filtrete furnace filters offered by 3M:

Best furnace filters - 3M Filtrete Product Line

3M Filtrete Product Line – Click to Enlarge

A Word About “The Program”


When it comes time to replace your furnace or air conditioner, make sure that you do your research.  Here’s a short video on program that can help:


The Best Furnace Filter for Your Money

Ok, so you’ve done the research, you’ve read the above topics, and you’re now an expert on furnace filters – so, which should you choose?  As we stated above, the best furnace filter is a filter that provides great filtration for your home, but is not so restrictive on your furnace that it blocks proper air flow.  That would make your furnace work harder to circulate air around your house, and could possibly even lead to your furnace “short-cycling.”  More on that can be found here:

Furthermore, we want a quality product, that isn’t too expensive.  So, in our opinion…drum-roll…the best furnace filter for all around, general use is:

The 3M Filtrete, Ultra-Allergen 1500 MPR Air Filter

Best furnace filter - 3m Filtrete Ultra-Allergen 1500

The best furnace filter – 3m Filtrete Ultra-Allergen 1500 – aka, “The 3M Purple”

For those of you worrying about remembering the ratings, 3M also color-codes their furnace filters.  So, if you can’t remember “1500,” then just remember that “the 3M purple filters.”   In our opinion, these are the best furnace filters for general use.

3M Filtrete 1500 Ultra-Allergen, “Purple” Filter Pros:

  1. It provides nominal filtration for your furnace, removing most particles from the air, protecting your furnace’s internal components, while also providing adequate air flow to your furnace.
  2. It also provides above average protection from common household allergens, such as dust, mold, dust-mites, etc.
  3. Prices vary based on the required size, but you’ll typically find them for around $20 each, or $90 for a year and a half supply on places like Amazon, available here: Amazon – 3m Filtrete Ultra-Allergen Filter 1500.

3M Filtrete 1500 Ultra-Allergen, “Purple” Filter Cons:

  1. This can add up to $60-$80 per year, but think of this as an insurance plan for both your health, as well as the longevity of your furnace.  The best furnace filter will cost some money, but in the long run, the cheap filters will cost you more – the premature replacement of your furnace.
  2. For people with severe allergies, asthma, or a compromised immune system, this might not be enough for you.  Consideration should be given to a higher MPR value, which we’ll discuss in the next section.

The Best Furnace Filter for Allergies, Asthma, or a Compromised Immune System

For most people with allergies or asthma, the 3M Purple Filter shown above will be plenty of filtration for you.  My wife has moderate to severe asthma, uses her rescue inhaler daily, and for what it’s worth, we use the 3M Purple Filters, and she has noticed a great improvement.  What I am saying is this: this section is for people who either have, or someone in their house who has, severe allergies, asthma, or a compromised immune system from chemotherapy, etc.  Although I can’t guarantee any results from the use of a furnace filter, I will tell you that 3M makes a “Nuke Option” for allergens and asthma – that is what we will now take a look at the best furnace filter for allergies and asthma:

The 3M Filtrete Healthy Living 2800 MPR Air Filter

Best furnace filter for allergies and asthma - 3m filtrete healthy living 2800

3m Filtrete Healthy Living 2800

This filter by 3M is known as the “3M Black Filter” in the industry, and it is the best furnace filter that I know of, excluding custom, multi-phased filters which we put in emergency rooms and things of that nature.  If someone in your home is suffering from allergies, even after trying the Purple 3M Filter, I’d give this a try.  You can find them here on Amazon: Amazon – 3m Filtrete Healthy Living 2800.

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Final Thoughts on the Best Furnace Filter

The word “best” is subjective, so in this article, we were hopefully able to define our terms and provide you with our insights into the best furnace filter available for you.  Whether it’s the best furnace filters for allergies and asthma, or just for general use, I truly do think that 3M has the best products…and no, we don’t get paid to say that – we’re straight-shooters, remember?  I hope you’ve found this article helpful.  For more articles like this, try our ASM Furnace Blog.

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Timothy Kautz
About the author
Tim K.

The University of Virginia - 2005 / The Wharton School of Finance - 2016 / U.S. Naval Aviator 2005-2015. At All Systems Mechanical air conditioning and heating, we believe that the experience our clients have is every bit as important as the products they receive. Simply put, our results speak for themselves, and we'd be happy to help. If you're in the market for a new AC or furnace, make sure that you get a fair price! Try our online calculator; click the tab on the top of this page for more information.

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