How to Select the Right MERV Rating for Your Furnace Filter

Figuring out the right MERV rating for your furnace filter can be tricky. There are various types of filters to choose from, and it might be difficult to select a filter that best fits your needs. We’re here to help. TML Service Experts is your local HVAC Expert in Boise, helping you make smart decisions for your home.

Choosing the correct furnace filter is all about matching indoor air quality with your HVAC system’s capabilities. Finding filters with the right MERV ratings is critical to ensuring your air is healthy without overworking your HVAC system.

What Does MERV Mean?

A minimum efficiency reporting value, or MERV is a rating system designed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). MERV ratings signify an air filter’s effectiveness at reducing airborne particles and contaminants. A filter’s rating is determined by the smallest particle it’s capable of trapping (measured in microns). As filters become better at improving indoor air quality, their MERV rating goes up, ranging from 1 to 20.

Below, you will see a chart that can help you determine the necessary MERV rating for a variety of settings.

MERV Range Controlled Contaminants Typical Application Air Filter Types
1-4 Pollen, Dust, Spray Paint, Dust Mites, Sanding Dust, Textile & Carpet Fibers Residential, Window AC Units Disposable Electrostatic
5-8 Mold Spores, Pet Dander, Hair Spray, Dusting Aids, Fabric Protector, Cement Dust, Pudding Mix Better Residential, Commercial, Industrial Workplaces Pleated Filters Cartridge Filters Electrostatic
9-12 Legionella, Auto Emissions, Lead Dust, Humidifier Dust, Welding Fumes Superior Residential, Better Commercial, Hospital Labs Pleated Filters Cartridge Filters
13-16 Bacteria, Droplet Nuclei (Sneeze), Tobacco Smoke, Insecticide Dust General Surgery, Hospital Inpatient Care Bag Filters Box Filters
17-20 Viruses, All Combustion Smoke, Carbon Dust Cleanrooms, Radioactive & Carcinogenic Materials, Pharmaceutical Manufacturing HEPA Filters Specialized Filters

Other Measurement Systems

Familiarity with MERV ratings might not be enough when you need to buy your furnace filter. For example, some big retailers use the filter performance rating (FPR), which goes from 1-10 and measures a filter’s ability to trap large and small particles. You might also see the microparticle performance rating (MPR) system, which ranges from 300 to 2200 and measures a filter’s effectiveness at capturing only the smallest particles on the MERV scale (0.3-1 microns in size).

You can use the chart below to better understand how filters rated with FPR and MPR compare to the more standard MERV rating system.

MERV Rating FPR MPR
MERV 1-5 Below Minimum FPR Below Minimum MPR
MERV 6 Below Minimum FPR MPR 300
MERV 8 FPR 5 MPR 600
MERV 11 FPR 7 MPR 1000-1200
MERV 13 FPR 10 MPR 1500-1900
MERV 14-20 Above Maximum FPR MPR 1900+

What Should My Furnace Filter’s MERV Rating Be?

Getting the right MERV rating for your air filter is a delicate balance between your HVAC system’s capabilities and the indoor air quality you want to have.

For example, a better MERV rating doesn’t always mean that a filter is the best option for your furnace. In fact, as MERV rating goes up, air flow goes down—forcing your HVAC system to work harder to push air through your furnace, increasing the possibility of a potential breakdown. Before buying a new furnace filter, be sure to check if your HVAC system has a maximum MERV rating. If it does, be sure to buy a furnace filter with a MERV rating below your system’s limit.

If your family has allergy problems or serious respiratory problems like asthma, you may want to invest in filters with higher MERV ratings. Remember, there are always other options available to improve your indoor air quality if your system is unable to handle the MERV ratings you need.

Generally speaking, our recommended MERV rating for furnace filters runs from 6 to 8 for a fantastic balance between top furnace efficiency and home comfort.

Choosingthe right MERV rating for your furnace filter has a huge impact on your indoor air quality, your HVAC system and, most important, your family’s well-being. Let TML Service Experts help you make a smart decision. We have a full line of air filtration options plus our Expert knowledge and service—and we’re available 24 hours a day for emergencies. Contact us at 866-397-3787 to schedule your indoor air quality consultation in Boise today!