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What's a MERV Rating?

Understanding the rating of your Air Filter

Every air filter on the market is assigned a MERV rating, but do you know what it means? MERV is an acronym that stands for Minimum Efficiency Reporting Values. The MERV rating tells you about a filter's ability to capture larger particles between 0.3 and 10 microns. 

So, why should we care about a MERV rating?

  • This number is helpful in comparing the performance of different filters. The higher the rating, the more particles the filter will capture!

  • The rating is derived from a test method developed by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE). That means this is a tried and true way to ensure your filter captures particles.

What do the different numbers mean? Here's a quick breakdown of what you can expect, and this can help advise you on what rating might be good for your home.

MERV 5-8

Catch finer dust particles, mold spores, aerosol spray particles, and pet dander.

MERV 9-12

Capture automotive emissions, welding fumes, lead dust, and larger bacteria.

MERV 13-16

Collect a larger range of bacteria, smoke particles, oil droplets, and fine particles from sneezing.

MERV 17-20

Can catch viruses, carbon dust, and the smallest smoke particles.

You’ll probably never need to use those filters at the top of the MERV rating list, but if there are people in your home with asthma or sensitive airways, you may consider using filters with a 10 - 14 MERV rating.


When we discuss MERV ratings, people often ask what the difference is between MERV and HEPA. HEPA stands for High Efficiency Particulate Air. HEPA filters are a type of air filter designed to capture at least 99.97% of particles that are 0.3 – 1.0 microns. Typically, filters with a high MERV rating are considered to be HEPA, meaning the filter will capture 99.97% of particles that are 0.3 - 1.0 microns in size. So, MERV and HEPA are related. For a filter to be HEPA, the MERV rating is 17 or higher.

If you need help determining which size or type of air filter you need, or if you need someone to change your air filter for you, schedule an appointment with Stanfield. We'll be happy to help you!


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