How Do Air Filter Ratings Work?

We harp on the importance of air filters all the time. Many families think changing them often is unnecessary and too expensive, but this couldn’t be further from the truth. Air filters actually make the air in your home more healthy by removing harmful particles, helping you breathe easier. In this post, we’ll take a look at why filters are so important, and what the different air filter ratings mean.


Air filters work by cleaning the air as it circulates through your HVAC system, removing harmful particles and contaminants before they re-enter your home. Contaminants in the air can include lint, dust, dirt, pollen, mold, dander, bacteria, and viruses.


Filter ratings are determined by the size of particles that can pass through. The smaller the micron filtration, the better the quality of the filters. Higher quality filters will mean cleaner air but are also a bit more expensive.


MERV ratings are the most common, so we’ll focus on what each rating range means.

  • MERV 1-4: The lowest MERV ratings are the least expensive and offer basic filtration. They capture particles that are 10 microns or larger. This includes pollen, dust, pet dander, and lint. You should change them out regularly.
  • MERV 6-8: Mid-range MERV filters capture particles as small as 3 microns. They catch everything that a low-rated filter would, as well as mold, hair spray, and dust mites. These filters work great for most homes.
  • MERV 9-12: The next step up captures particles as small as 1 micron! This means they can catch auto emissions, flour, and finer forms of dust. This rating is recommended for families with allergies, asthma, or other respiratory issues.
  • MERV 13-16: The highest-rated MERV filters capture particles as small as 0.3 microns. These are used in hospitals or manufacturing facilities to eliminate bacteria, viruses, carbon dust, and even sneeze droplets.


The Bosworth Company has experts to tackle all your HVAC needs. Fall is an excellent time for our Fall Clean & Check, which provides a tune-up for your complete system, as well as a free 1-inch air filter! Call us today at 432-570-5233 to make an appointment or schedule one online. The Bosworth Company. Worth the Call. Always.