What Is a MERV Rating?

Ever found yourself lost in the HVAC filter aisle at your local store? With numerous brands, sizes, and efficiency ratings to choose from, selecting the right air filter can feel like navigating a maze.

Amidst this confusion, understanding air filter efficiency becomes crucial. Enter MERV ratings – a vital component of air filtration that impacts indoor air quality significantly. HVAC.com answers the question, “What is a MERV rating?” and explains how it can influence your home’s air quality.

What Is a MERV Rating?

MERV stands for Minimum Efficiency Reporting Value.

Every air filter is assigned a MERV rating, which measures the effectiveness of air filters in capturing larger airborne particles between 0.3 and 10 microns in size which may include dust mites, bacteria, pollen, mold spores, and pet dander.

MERV Rating Chart

Selecting the appropriate air filter is essential for safeguarding both your home’s indoor air quality and the longevity of your HVAC system. Air filters with a low efficiency rating may not effectively capture airborne particulate matter, while a high-rated MERV filter may be too restrictive for your HVAC system, leading to decreased airflow and potential strain on the system’s components.

The MERV rating chart typically ranges from 1 to 20.

• MERV 1-4: These basic and budget-friendly models are commonly used in residential settings, offering protection primarily against larger particles such as dust, pollen, and lint. These filters are the least restrictive and trap the lowest amount of contaminants.
• MERV 5-8: Filters with these ratings offer better overall filtration capabilities are commonly found in homes where moderate air quality is desired. They are more effective at capturing smaller particles including pet dander and mold spores. It’s crucial to consider that for both budget and efficiency, MERV 8 filters may be the optimal choice for most homes, as they are typically well-suited for residential HVAC systems.
• MERV 9-12: Filters falling within this range offer high-efficiency filtration, effectively trapping finer particles like pollen and fine dust. MERV 9-12 filters can be suitable for homes, but they may be too restrictive for certain HVAC systems. Consult your owner’s manual to ensure compatibility with your HVAC system.
• MERV 13 and Higher: Filters with MERV ratings of 13 and higher are typically used in environments where stringent air quality standards are essential, such as hospitals, laboratories, and cleanrooms. They are not commonly found in residential homes.

Click here to view the U.S. Environmental Protection Agency's chart detailing MERV ratings and their corresponding average particle size efficiency in microns.

Choosing the Right MERV Rating for Air Filters

When choosing the right MERV rating for your air filters, consider factors like indoor air quality needs, sensitivity to allergens, and HVAC system compatibility. While higher MERV ratings offer better filtration, they can also strain your HVAC system if not compatible, so consulting with a professional is crucial. By selecting the appropriate MERV rating, you'll improve indoor air quality and extend your HVAC system’s lifespan, ensuring cleaner, healthier air in your home or business.