Understanding the mechanics of air filters isn’t always easy. Here’s some added context to illustrate MERV vs FPR vs MPR ratings, the purpose of air filter pleats, and some key differences between brands.

As with any industry niche and product there’s always some revelations that come naturally on the learning curve. For most our customers it’s learning about air filter ratings. The second is pleating.

Despite filtration ratings being set by an official governing organization, not all filters are created equal. Ratings designate what filters should extract from the air. Ratings do not equate to filter quality. This concept is reminiscent of a quote from the movie, “Days of Thunder.” In this movie starring Tom Cruise and Robert Duvall, Duvall plays a well-known race car builder and he emphatically states at one point, “There’s nothing stock about a Stock Car.”

Turns out it’s the same when considering home air filters—there are many subtle differences that make up the quality of a filter, and consequently these quality differences play a big part in the quality of air you breathe at home, and how frequently you’ll need to change them out.

Image showing air filtration and showing MERV Ratings explanation, Indoor Wellness, Best in Home Air Filter Subscription Services


MERV rates a filter’s ability to capture and hold certain sized particles and pollutants. The Rating system was established by ASHRAE (American Society of Heating, Refrigeration, and Air Conditioning Engineers and is the primary rating system used by industry professionals both domestically and internationally.


All filters are rated. But, not all ratings are the same. Air filtration ratings are governed by the American Society of Heating, Refrigeration, and Air Conditioner Engineers (ASHRAE). ASHRAE is a non-profit entity that provides standards, regulations and guidance regarding products and practices in the industry. They developed the standard MERV rating system (Minimum Efficiency Reporting Value) by which all licensed professionals use, and most companies and manufacturers adhere to.

However, there are those that decided to build their own rating system. Home Depot, via Honeywell, has decided to determine their own rating. And, Lowe’s with Filtrete have their own separate rating system they created.

Some assume Home Depot’s or Lowe’s rating was universal. It’s common misunderstanding. Turns out that Home Depot’s marketing department decided they’d try and capitalize on their own brand strength and aimed to create a rating system (FPR, Filtration Particle Rating) to set them apart. Which, worked, but it’s also made it more difficult to compare ratings between one brand and another. Filtrete/3M did the same thing naming their rating system called MPR (Microparticle Performance Rating). Lowe’s typically carries this brand. A few have since added comparable charts, which are shown here for your convenience.

Indoor Wellness
Home Depot/
8-9 1000 7, Red Pollen, sanding dust, textile fibers, carpet fibers, paint overspray, mold, spores, dusting aids, and cement dust
10-11 1900 9, Purple Everything above, plus large bacteria, pet dander, smaller dust particles, and auto emissions
12-13 2200 10, Black Everything above, bacteria, cooking oil smoke, smog, tobacco smoke, and droplet nuclei (sneeze)


Bob Vila, the renowned Home Improvement Expert, says this about air conditioner air filter ratings: “You might think that a higher MERV rating would automatically be better, but it’s not. The higher the MERV rating, the smaller the pores are for air to flow through an HVAC filter. This can create more resistance in airflow than a system is designed to manage, thus making it inefficient. Reducing the air flow in your system can actually worsen the air quality in your home and put a damaging amount of pressure on the fan of your furnace or AC system.”

Contrary to this renowned expert, Home Depot still persists that, “The higher the number the better air filter performance, as rated by The Home Depot.”

Indoor Wellness is a company recommended by HVAC and IAQ experts, rather than by celebrities and wanna-bes. We agree with Bob Vila’s conclusions—echoed by every other HVAC expert—and it’s the exact reason why Indoor Wellness doesn’t sell a MERV 13. Instead, we offer a Carbon+ MERV 8 filter that performs the exact same functions as a MERV 13, but provides improved airflow and is actually better for your system and consequently air quality. Yes, it’s slightly more expensive, but it’ll last longer and perform better. The carbon cleans the fumes, smoke and smells from the air versus attempting to filter it—making it our clear choice for better air quality.

Our most popularly purchased filter tends to be the MERV 11, Select Filter.

Have a Question? Ask an Air Filter Expert.