How to Select the Right MERV Rating for Your Furnace Filter

Determining the right MERV rating for your furnace filter can be tricky. There are various types of filters to choose from, and it might be hard to select a filter that best fits your needs. We’re here to help. San Antonio Air Service Experts is your local HVAC Expert in San Antonio, assisting you in making informed decisions for your home.

Choosing the correct furnace filter is all about balancing indoor air quality with your HVAC system’s capabilities. Getting filters with the right MERV ratings is essential to ensuring your air is healthy without overly taxing your HVAC system.

What Does MERV Mean?

A minimum efficiency reporting value, or MERV is a measurement 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 minimum size particle it’s capable of trapping (measured in microns). As filters become better at improving indoor air quality, their MERV rating increases, ranging from 1 to 20.

Below, you will find 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 the time comes to purchase 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 come across the microparticle performance rating (MPR) system, which ranges from 300 to 2200 and measures a filter’s effectiveness at trapping 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 ranked with FPR and MPR stack up 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?

Choosing the right MERV rating for your air filter is a balancing act between your HVAC system’s capabilities and the indoor air quality you want to achieve.

For example, a higher MERV rating doesn’t always mean that a filter is the best option for your furnace. In fact, as MERV rating increases, 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 limit for MERV rating. If it does, be sure to buy a furnace filter with a MERV rating that’s lower than your system’s limit.

If your family has allergies or serious respiratory problems like asthma, you may want to invest in filters with higher MERV ratings. Remember, there are always other options out there to improve your indoor air quality if your system can’t handle the MERV ratings you require.

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

Selecting the right MERV rating for your furnace filter has a major impact on your indoor air quality, your HVAC system and, most important, your family’s well-being. Let San Antonio Air Service Experts help you make the right decision. We have a complete line of air filtration options in addition to our Expert knowledge and service—and we’re available 24/7 for emergencies. Contact us at 866-397-3787 to schedule your indoor air quality consultation in San Antonio today!