Filter Knowledge

Air Filter MERV Ratings Guide: What Should You Buy?



The proverb “you can’t eat your cake and then still have it” beautifully explains how MERV ratings work. If you are not familiar with this proverb, it is basically saying that in life you cannot always have things two ways. With MERV ratings, a higher MERV rating will capture more airborne particles but will restrict air flow while a lower MERV rating will capture fewer airborne particles but will help maintain a higher flow of air.

Basically, if you want to improve air quality, you will have to sacrifice heating and cooling performance. While at the same time, if you want to save money on your utility bill, you might have to live with the pollen, dander, bacteria and other airborne particles.

The reality is it isn’t so black and white, but it can help to understand the differences between MERV 8, MERV 11, or MERV 13 air filters. Regardless of your choice, you won’t completely clog your heating and cooling system, nor will your air become completely unbreathable. But it still helps to learn about the differences between each of these filters so you can make an informed decision!

Do You Prioritize Air Flow or Improve Air Quality?

The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) sets the standard for MERV ratings. There are two methods used to judge the filter’s ability to capture airborne contaminants that are most important to consumers. The first is “Air Filter Efficiency,” which describes the measure of microscopic particles the filter can remove from the atmosphere (pollen, dander, bacteria, emissions.) The second is “Air Filter Arrestance,” which describes how well an air filter will capture larger particles (hair, dust, lint, etc.).

How air filter manufacturers meet these standards is somewhat simple. All pleated air filters (one of four types of air filters for the home), like those sold on, use synthetic fibers that are woven together to form a semi-rigid panel. Because the panel is not solid, it has pores that allow air to pass through. To increase the MERV rating, we simply add more fibers, which shrinks the size and number of pores. And vice verse for lower MERV ratings. As we increase or decrease the fibers, we directly impact the amount of air and contaminants that can pass through the panel.

Okay, now it is time to choose the right MERV rating for your air filter.

MERV 8 Ratings – Best Air Flow

MERV 8 air filters are ideal for the homeowner that is satisfied with their existing air quality and that wants to save on their utility bill during the summer and winter months.

What MERV 8 Air Filters Reduce:

  • Dust
  • Pollen
  • Dust Mites
  • Lint
  • Mold

These filters benefit from a much higher air flow, but they remain effective at reducing many home allergens and other particles that can affect indoor air quality. If you currently use a fiberglass filter, a MERV 8 filter is the best way to transition into a more modern, pleated air product.

MERV 11 Ratings: Balanced Air Flow and Air Quality

MERV 11 air filters are the most popular, and they are an ideal choice for home filtration. These filters provide a good balance between maintaining air flow through the home and reducing airborne contaminants.

What MERV 11 Air Filters Reduce:

  • Lead Dust
  • Automotive and Industrial Emissions
  • Hair Spray
  • Synthetic Cleaners

If anyone in the home has mild to moderate allergies, you have small pets, or struggle to keep surfaces free of dust, then a MERV 11 filter will satisfy most of your needs without making too big of an impact on air flow or utility costs.

MERV 13 Ratings: Improved Air Quality

MERV 13 air filters are ideal for anyone with severe allergies or other respiratory issues, those that live with tobacco smokers, or those that want to see their indoor air quality improve in the shortest possible amount of time.

What MERV 13 Air Filters Reduce:

  • Smoke
  • Bacteria and Viruses
  • Synthetic Cleaners
  • Automotive and Industrial Emissions

Before rushing to a MERV 13 filter, keep in mind that these filters will affect air flow through the home, and if indoor air quality isn’t great, the filter will need to be replaced sooner than expected because it is working extra hard to capture everything that’s already in the air.

A Word About Trying Different MERV Ratings

If you currently use a MERV 8 air filter and you decide to step up to an 11 or 13, you might find that the air filter needs replaced more frequently. This isn’t because of a faulty design, rather the lower rating allowed more particles to slip past the filter that will now be captured. Likewise, if you step down from a MERV 13 air filter to an 11 or 8, don’t be surprised if indoor surfaces dirty more quickly and there are more odors in the air.

To get the most from your filter, make sure to check them every 30 days and replace them when the material becomes discolored, or the filter is visibly clogged. Failure to replace air filters can cause the heating and cooling system to work harder than necessary and result in more expensive utility bills.

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