MERV Ratings: MERV 13 vs MERV 11 vs MERV 8

Indoor air quality may not be something that crosses your mind until you start sneezing or your allergies flare up. But it’s important to note that indoor air is 2 to 5 times more polluted than the air outside on average, which is problematic for the 50 million Americans who suffer from allergies and the 25 million with asthma.

While some homes can benefit from the installation of whole-house air purification devices such as air cleaners and air purifiers, the first line of defense against indoor air contaminants and pollutants is an efficient and effective HVAC air filter. Your heating and cooling system’s air filter is tasked with removing dust, pollen, allergens, spores, and other microorganisms that affect the quality of your indoor air each day.

When choosing the right furnace filter for your home, the air filter’s MERV rating is a good place to start. There are many different types of filters, each providing a different level of protection against indoor pollutants.

What Is a MERV Rating?

HVAC air filters are rated by Minimum Efficiency Reporting Value, or MERV rating. This is a simple system for rating a filter’s ability to capture particles based on their size in microns.

The rating is given based on a method of testing developed by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) and is helpful in determining which air filter will work best for your heating and air conditioning system and indoor air quality goals.

According to the United States Environmental Protection Agency, the MERV rating is set on a scale from 1 to 16. The number is assigned based on a filter’s ability to capture particles that range in size from 0.3 and 10 microns. For most homes and commercial buildings, filters with a MERV rating between 8 and 13 will sufficiently filter the air.

When shopping for a home air filter, most people will review a MERV 8 vs. MERV 11, or, for homes where allergies and asthma are a high consideration, choosing between a MERV 11 vs. MERV 13 filter may be more beneficial. Let’s break down what separates these filters and which one is right for you.

What Does a MERV 8 Filter Capture?

According to the EPA, a MERV 8-rated filter captures at least 70% of particles between the sizes of 3.0 and 10 microns. This is typically good enough to get the job done for the average home.

However, a MERV 8 filter captures greater or equal to 20% of particles between 1.0 and 3.0 microns and is not rated to filter particles or pollutants between the sizes of 0.30 and 1.0 microns. That means things like pet dander, smoke, and some airborne bacteria are likely to get through a MERV 8 filter.

What Does a MERV 11 Filter Capture?

A MERV 11-rated filter captures 85% or better of particles between the sizes of 3.0 and 10 microns, according to the EPA.

For pet owners specifically, a MERV 8 vs. MERV 11 filter can make a noticeable difference.

The MERV 11 filter is better at capturing pet dander and bacteria from sneezes. It also provides additional protection against smoke, smog, or automobile exhaust fumes that may seep in from the garage.

A MERV 11 filter is capable of filtering at the following rates:

• 0.30-1.0 size microns greater than or equal to 20%
• 1.0-3.0 size microns greater than or equal to 65%
• 3.0-10.0 size microns greater than or equal to 85%

What Does a MERV 13 Filter Capture?

A MERV 13-rated filter captures 90% or better of particles between the sizes of 3.0 and 10 microns. The higher-rated filter also captures up to 50 percent or greater of the smallest particles floating through the air.

The primary benefit when comparing a MERV 11 vs. MERV 13 filter is that the latter includes stronger protection against airborne bacteria and viruses that spread through droplets in the air.

• 0.30-1.0 size microns greater than or equal to 50%
• 1.0-3.0 size microns greater than or equal to 85%
• 3.0-10.0 size microns greater than or equal to 90%

Best MERV Filter Ratings for Home

There are three ways to be more specific in determining the air filter MERV rating for the air filters you use in your home:

• Evaluate your family’s lifestyle. If you have pets, opt for at least a MERV 11 filter. You’ll want a filter that captures the pet dander and loose hair. If there’s smoking in the home or allergies or asthma affect your family, go for a MERV 13.
• Consider environmental factors. Living in Los Angeles comes with environmental challenges that those in Cumberland, Rhode Island don’t face. If you live in a smog city or otherwise poor air quality space, install a higher MERV-rated filter in your home. Homeowners in rural areas are often shielded from pollutants with a MERV 8 filter.
• Ask an expert. If you’re still unsure which filter MERV rating is best for your home, speak with an HVAC expert who can guide you to the right selection.

What MERV Rating Filter Is Right for My Commercial Property?

Strict building codes and an increase in foot traffic generally mean commercial properties should opt for a filter with a higher MERV rating. To protect the well-being of your employees and customers, install at least a MERV 13-rated filter in your commercial building.

MERV 13 filters help protect against the spread of bacteria, sneeze particles, smoke, and virus-carrying germs. If your commercial space offers any type of health or medical services, speak with an HVAC specialist about your special needs.

MERV 14, 15, and 16 filters are typically used in specialized applications where high-level filtration is required, such as hospital operating rooms and other environments where capturing even the smallest particles, including bacteria and viruses, is crucial.

Although some sites online discuss MERV 17-20 filters, the EPA and ASHRAE only rate filters on the MERV 1-16 scale. However, the EPA notes that high-efficiency particulate air filters (HEPA filters) are capable of theoretically removing at least 99.97% of mold, dust, pollen, bacteria, and airborne particles with a size of 0.3 microns.

Best MERV Rating Filter for Viruses

Using a MERV rating 13 filter is best for shielding against virus-spreading bacteria, but adding air quality solutions to your home should also be considered. An air filter alone is not a guarantee against airborne viruses like COVID-19, the flu, or the common cold.

For spaces where higher indoor air quality is needed, consider adding a portable air purifier or a whole-house air purifier that attaches directly to your HVAC system. Many of these devices can create cleaner air in a large space in a relatively short amount of time.

Should I Use the Highest MERV Rating Filter Available?

The heating and cooling system that supports your home needs an adequate amount of airflow to operate smoothly. Using the highest MERV rating filter in your home would restrict that airflow, making it difficult for your HVAC to function properly which can lead to breakdowns and premature system replacement.

Filters with a MERV rating above 13 are woven together tightly to capture potentially harmful pollutants. That restrictiveness would make it hard for the air to circulate from your home into the unit.

Stick with a MERV 8 to 13 filter, depending on your family’s needs and environment, and begin using an indoor air quality monitor to help you determine if a separate air purifying system is needed.

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FAQs on MERV Ratings

What MERV rating do I need?

The MERV rating you need depends on various factors such as your specific indoor air quality concerns, HVAC system compatibility, and recommendations from professionals. If you have family members with allergies, asthma, or other respiratory conditions, consider using a MERV 13-rated filter.

What does MERV stand for?

MERV stands for Minimum Efficiency Reporting Value and determines an air filter’s efficiency at capturing particles based on their size in microns.

What does MERV 8 mean?

According to the EPA, a MERV 8 filter means it is capable of capturing 20% or greater of particles 1.0 to 3.0 microns in size and 70% or greater of particles 3.0 to 10.0 microns in size.

What MERV rating is best?

The best MERV rating depends on your specific indoor air quality needs and other factors. Based on a scale of 1-16, the higher the MERV rating, the better the filter is at capturing contaminants and pollutants.