Air Filter Guide: What MERV Rating Should You Use?

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When it comes time to replace your home’s air filter, it’s easy to get overwhelmed with all the different options available.

For instance, the last time I went to the hardware store there was an entire aisle that was dedicated to just air filters! That’s right—air filters in nearly every size, thickness, material, and MERV rating.

Today I’m going to talk about that last one—the MERV rating.

Depending on your situation, one MERV rating will be more appropriate than another.

Below I’ll discuss what to look out for when selecting an air filter and what MERV rating is best for your home.

Table of Contents

What MERV Rating Should You Use?

Since a high MERV rating means that more particulates will be removed from the air, you may think that air filters with the highest MERV rating are best.

However, a high MERV rating on an air filter usually means that the filter is thicker—your HVAC system will have to work harder to circulate air through your home.

When your HVAC system works harder, it uses more energy and experiences more wear and tear.

Using an air filter with a MERV rating of about 5 to 8 is appropriate for most residential homes.

MERV 5 – MERV 8 filters provide good filtration and will remove most pollen, mold spores, and dust mites.

Using MERV 5-8 filters will keep your HVAC system more efficient than using higher-rated filters, as long as you replace your filters regularly.

There are two main types of air filters: pleated and non-pleated. Generally, pleated filters have a higher MERV rating, while non-pleated filters have a lower one.

Using an air filter with a MERV rating of about 10 to 12 is appropriate for filtration against allergens.

If you are susceptible to allergens, then you may want to use a filter with a MERV rating of about 10 to 12.

MERV 10 – MERV 12 air filters can trap particles as small as 1 micron such as automobile exhaust, pollen, and mold spores.

Sometimes particles such as pollen, pet dander, and fine dust can sneak by your filter unless you get one with a higher MERV rating.

A filter with a MERV rating of around 10 to 12 is sufficient to remove most allergy-causing particles from your home’s air.

Most air filters that can remove common allergens will have the word “allergy” or “allergen” on their packaging. This is an indication that you’re on the right track.

Some of the best air filters for allergies have extra features such as a carbon layer to remove odors. These are suited for people who have pets or other sources of smells in their homes.

One thing to keep in mind is that not all HVAC units can accommodate air filters with higher MERV ratings.

Some air filters, especially those with higher MERV ratings, may impede airflow due to enhanced air filtration.

Check out my article below on how MERV rating affects airflow for more information:

Do High-MERV Filters Restrict Airflow?

What Is the Best MERV Rating to Use?

Depending on your air filtration needs, there is a MERV filter that meets your requirements.

The table below shows the different MERV ratings and their typical uses as well as the typical material and shape that they are made of.

MERV Rating Comparison Table

MERV Rating	Description	Application	Typical Air Filter Material
MERV-1 to MERV-4	Basic filter Blocks carpet fibers and lint, but unable to block out much else.	Light Residential Window/Split AC	Fiberglass Washable aluminum Synthetic mesh
MERV-5 to MERV-8	Typical filter Blocks out common dust, pollen, and some mold spores.	Typical Residential Typical Commercial	Pleated cotton Polyester
MERV-9 to MERV-12	Better filter Blocks out most mold spores, smog, fine dust, and pet dander.	Allergies Better Residential Better Commercial	Pleated cotton Microfine fiberglass Usually 2" thick or more
MERV-13 to MERV-16	Superior filter Blocks out bacteria, viruses, smoke, and other microscopic particles	Severe Allergies Hospitals Smoking Lounges	Pleated cotton Microfine fiberglass Usually 4" thick or more

How Does the MERV Rating System Work?

The MERV system is the industry-standard air filter rating system. It was established by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE).

ASHRAE standard 52.2 describes the methods and procedures for evaluating the performance of air filters as a function of particle size. In layman’s terms, it sets forth the minimum amount of particles that a filter must capture to obtain a specified MERV rating.

For instance, if an air filter can capture at least 20% of E1, 65% of E2, and 85% of E3 particles, then it will obtain a MERV 11 rating.

Air Filter MERV Rating Definition

MERV stands for Minimum Efficiency Reporting Value. The MERV rating system is intended to be used to determine the filter’s ability to remove particulates from the air.

An air filter’s MERV rating is a scale from 1-16 that describes the minimum efficiency of the air filter. A low MERV rating means that the filter does not remove as many particulates from the air.

Conversely, a high MERV rating indicates that the filter does a good job of removing particulates from the air.

Air Filter MERV Rating Specifications

The table below shows the minimum threshold that a filter must perform to obtain a specified MERV rating. As the MERV rating goes up, the filtration efficiency requirements get more stringent.

MERV Rating Parameters

	Minimum % of particles removed by air filter
MERV Rating	E1 particles (0.3 - 1.0 microns)	E2 particles (1.0 - 3.0 microns)	E3 particles (3.0 - 10.0 microns)
MERV-1	-	-	<20%
MERV-2	-	-	<20%
MERV-3	-	-	<20%
MERV-4	-	-	<20%
MERV-5	-	-	>20%
MERV-6	-	-	>35%
MERV-7	-	-	>50%
MERV-8	-	>20%	>70%
MERV-9	-	>35%	>75%
MERV-10	-	>50%	>80%
MERV-11	>20%	>65%	>85%
MERV-12	>35%	>80%	>90%
MERV-13	>50%	>85%	>90%
MERV-14	>75%	>90%	>95%
MERV-15	>85%	>90%	>95%
MERV-16	>95%	>95%	>95%

Higher-rated MERV filters must not only be able to filter out smaller particles but more of them as well.

It should also be noted that filters on the lower end of the MERV scale are not even tested for efficiency at capturing E1 and E2 particles. That doesn’t mean that they won’t capture any E1 or E2 particles – it just means that they aren’t proven to capture them at a specified level.

MERV Rating Testing: E1, E2, and E3 Particles

E1, E2, and E3 particles are particle range sizes that are used in testing air filters to determine a MERV rating.

Starting with E1, these are the smallest particles that are tested. E1 particles range in size from 0.3 to 1.0 microns in diameter. Typical particles in this size range are smoke particles and bacteria. Only filters with a rating of MERV 11 or higher are tested with particles in this size range.

E2 particles range in size from 1.0 to 3.0 microns. Typical E2 particles include pet dander and E. coli. PM_2.5 are particles that are 2.5 microns or less in diameter, so the largest PM_2.5 particles are considered E2 particles. Only filters with a rating of MERV 8 or higher are tested with particles in this size range.

E3 particles range in size from 3.0 to 10.0 microns in diameter. Typical E3 particles include common dust, pollen, and mold spores. Most air filters can capture E3 particles to some degree. However, higher-rated MERV filters can capture more E3 particles than lower-rated ones.

What Is the MPR Rating System?

The MPR rating system is an air filter rating system created by 3M.

The main difference between the MPR and MERV rating systems is that the MPR rating system is focused on a filter’s effectiveness at removing E1 microparticles from the air.

MERV vs. MPR Rating: What’s the Difference?

What Is the FPR Rating System?

The FPR rating system is a filter rating system that The Home Depot uses to rate air filters.

The main difference between the FPR and MERV rating systems is that the FPR rating system uses a scale of 1-10, while the MERV rating system uses a scale of 1-16.

For more information about the FPR rating system, check out my article below: