What Is a MERV Rating?

By Anne Fonda

Dust particles, pet dander, pollen, and other pollutants smaller than the eye can see are measured in microns. To give you an idea of how small a micron is, a human hair is 50 microns in diameter! Air filters are designed to capture tiny particulates. The higher the air filter MERV rating, the more effective the filter is at capturing allergens and pollutants before they can enter your HVAC system.

What Are the Different MERV Rating Levels and What Do They Mean?

MERV ratings range between 1 and 16. Performance above MERV 16 is rated as HEPA performance. A higher MERV rating indicates a more efficient filter, but it also means a more expensive system. 

The American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) developed a test method to test the effectiveness of air filters. MERV ratings are now an accepted air filtration rating system.

Not all HVAC systems can accommodate high MERV filters because of the pressure drop they can cause in the air pressure/airflow in your HVAC system. Your HVAC professional can recommend the best filters for your current system.

What MERV rating do I need?

It depends. MERV 8 filters are basic budget filters, but they don’t filter out some of the tiny particles that can irritate the respiratory system. This can mean decreased indoor air quality (IAQ).

A MERV rating between 9-12 or even higher would be good if someone in your family suffers from allergies or asthma. A MERV 11 filter can trap particles such as dust, dust mites, pollen, pet dander, mold spores, lint, and larger particles. 

In addition to filtering out everything a MERV 11 filter can, MERV 13 filters can filter out smoke, smog, some airborne viruses, and more. The Trane QuikBox™ Air Cleaner is a 4.7” filter available in both MERV 11 and MERV 13. 

For the ultimate in an HVAC filtration and air purification system, you may want to consider the Trane CleanEffects® Whole-Home Air Cleaner, which can remove 99.8% of airborne particles from the air before they enter your HVAC system. 

MPR Rating and What It Means

You might also see an MPR rating on an air filter. MPR stands for Microparticle Performance Rating. It measures a filter’s ability to capture smaller particles (from .3 to 1 micron) specifically. In many cases, these filters are pleated and electrostatic, enabling them to capture more particles than a standard fiberglass filter. 

Choosing the Right HVAC Air Filter

Choosing the right HVAC filter for your home will depend on your budget, if anyone in the home has allergies or asthma, if you have pets, and more. In general, the higher the MERV or MPR rating, the more particles and microparticles a filter will capture. That means cleaner air for everyone. 

Consider setting up auto-delivery of your HVAC air filters so that you always have a spare on hand. Trane partners with Filter Time to provide the Trane Comfort Performace filters with an MPR of 1000 and MERV rating of 9.

Changing your filter regularly helps your indoor air quality as well as helps your HVAC system run more efficiently. Clogged filters can cause asthma and allergy symptoms and put a strain on your heating and cooling system.

Consult with your local Trane Comfort Specialist for air filter and air purification product recommendations for your home.

Anne Fonda, Content Writer

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A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism.

When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

Expert review by Jennie Bergman, Senior Product Manager, Indoor Air Quality