All About Residential MERV Ratings

Did you know that not all furnace filters are created equally? When you walk down the filter aisle at the hardware store, they may all look similar, but it is a filter’s MERV rating that sets it apart from the crowd.

So what’s a MERV rating? MERV stands for Minimum Efficiency Reporting Value. This rating measures the efficiency of a furnace filter, telling you the filter’s effectiveness in removing household contaminants from your air supply. The higher the MERV rating, the more effective your filter will be.

Selecting the right MERV rating
For furnace filters used in residential settings, appropriate MERV values range from 1 to 16. While a higher MERV rating does mean the filter is more effective, it doesn’t always mean it’s the right choice. The openings of a high-rated filter are quite small in order to trap microscopic airborne contaminants; unfortunately, this can also restrict air flow through your heating and cooling system, which can damage your equipment. To find out which MERV rating is right for your HVAC system, ask your HVAC professional.
You should also consider the contaminant types that are present in your home when selecting a filter. Homes with pets or family members who suffer allergies require enhanced contaminant control and can benefit greatly from selecting a higher rated filter.
Residential MERV rating categories

MERV 1-4: Filters with MERV ratings of 1 to 4 are the lowest efficiency option. They trap less than 20 percent of particles that are greater than 10 microns in size. These filters may help remove some of the following contaminants from your indoor air supply, but it is recommended that you choose a higher efficiency filter for greater air quality improvement:
• Pollen
• Dust Mites
• Textile and Carpet Fibers
• Dust from Spray Paint or Sanding

MERV 5-8: Filters with MERV ratings between 5 and 8 are standard for residential applications. They are from 80 percent to more than 90 percent effective at removing contaminants that are between 3 and 10 microns in size. This includes contaminants such as:
• Pollen
• Pet Dander
• Dust and Lint
• Dust Mites
• Fine Dusts such as Pudding Mix or Cement Dust
• Mold Spores

MERV 9-12: Filters with MERV ratings of 9 to 12 are considered a superior option for residential applications, and are used in some commercial and hospital settings, too. Filters with a MERV rating of 11 and higher are best for households with asthma and allergy sufferers. Filters in this category trap greater than 90 percent to more than 95 percent of contaminants 1 to 3 microns in size. These contaminants include:
• Pollen
• Pet Dander
• Dust and Lint
• Dust Mites
• Mold Spores
• Welding Fumes
• Automobile Emissions
• Odors
• Fine Dusts including Flour, Humidifier Dust and Lead Dust
• Legionella

MERV 13: MERV 13 filters are generally the highest rated options that are appropriate for residential settings. They are more than 98 percent effective for removing contaminants which are less than 1 micron in size. These filters trap contaminant particles such as:
• Pollen
• Pet Dander
• Dust and Lint
• Dust Mites
• Mold Spores
• Air Pollution
• Odors
• Smoke
• Bacteria
• Sneeze Particles