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MERV Rating Chart Explained: Understanding 1-20 Ratings

During the process of recirculating clean air into a room, air filters trap minuscule particles, such as dust, dander, and even microorganisms. ASHRAE says that this kind of filtration improves air quality in factories, warehouses, and homes.

However, the efficiency of a filter is dependent on the filter’s design. The MERV rating of a filter shows how well it can remove these particles. However, MERV is still generally unknown by the wider public. In this guide, we’ll briefly go over what the MERC rating chart is, and how MERV filters differ from HEPA.

MERV RatingAir Filter will trap Air Particles size .3 to 1.0 micronsAir Filter will trap Air Particles size 1.0 to 3.0 micronsAir Filter will trap Air Particles size 3 to 10 micronsFilter Type – Removes These Particles
MERV 1< 20%< 20%< 20%Fiberglass & Aluminum Mesh
MERV 2< 20%< 20%< 20%
MERV 3< 20%< 20%< 20%Pollen, Dust Mites, Spray
MERV 4< 20%< 20%< 20%Paint, Carpet Fibers
MERV 5< 20%< 20%20% – 34%Cheap Disposable Filters
MERV 6< 20%< 20%35% – 49%
MERV 7< 20%< 20%50% – 69%Mold Spores, Cooking Dusts
MERV 6< 20%< 20%70 – 85%Hair Spray, Furniture Polish
MERV 9< 20%Less Than 50%85% or BetterBetter Home Box Filters
MERV 10< 20%50% – 64%85% or Better
MERV 11< 20%65% – 79%85% or BetterLead Dust, Flour
MERV 12< 20%80% – 90%90% or BetterAuto Fumes,Welding Fumes
MERV 13Less Than 75%90% or Better90% or BetterSuperior Commercial Filters
MERV 1475% – 84%90% or Better90% or Better
MERV 1585% – 94%95% or Better90% or BetterBacteria, Smoke, Sneezes
MERV 1695% or Better95% or Better90% or Better
MERV 1799.97%99% or Better99% or BetterHEPA & ULPA
MERV 1699.997%99% or Better99% or Better
MERV 1999.9997%99% or Better99% or BetterViruses, Carbon Dust, <.30 pm
MERV 2099.99997%99% or Better99% or Better

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What Exactly Is MERV?

The minimum efficiency reporting value (MERV) of an air filter indicates how well the filter prevents dust and other airborne particles from recirculating into the air. MERV ratings are used to determine how well a filter traps smaller particles.

MERV rating charts display the efficiency of a product by displaying the figure on the chart. There are 20 points on the chart, with 1 representing the lowest efficiency and 20 representing the highest efficiency.

Air Purifier MERV

Looking at MERV Ratings and Efficiency Levels

It’s important to remember that when selecting the best filter for your application, bigger is not always better. Using an air filter with a higher MERV rating than the one recommended by the manufacturer of your furnace or air conditioner can actually reduce the performance of your equipment by as much as 10%.

More highly rated air filters have smaller pores, which creates resistance to airflow. When used in an HVAC system that is not designed to withstand this resistance, the filter can reduce system efficiency, degrade indoor air quality, and place additional strain on the fan motor.

Now let’s take a closer look at the MERV ratings and see how effective they really are:

  • MERV 1-4 < 20% for 3-10-micron particles
  • MERV 6 ≤ 49.9% for 3-10-micron particles
  • MERV 8 ≤ 84.9% for 3-10-micron particles
  • MERV 10 ≤ 64.9% for 3-10-micron particles and ≤ 85% for 10-micron particles and larger
  • MERV 12 ≤ 89.9% for 1-3-micron particles and ≤ 90% for 3-micron particles and larger
  • MERV 14 ≤ 84% for 0.3-1-micron particles and larger and ≤ 90% for 1-3-micron particles
  • MERV 16 ≤ 75% for 0.3-1-micron particles and larger
Levoit Core 400S
Levoit Core 400S

A Higher MERV (M) value of a filter shows a more efficient filter. Filters with M values between 1 and 4 capture large particles. These filters are mostly used to keep personal protection equipment safe.

You will most likely find them in use at small-scale industrial plants and home projects. Between 3 and 10 microns, they aren’t very efficient at all. MERV 1 to 4 is given if the average arrestance value is at least 4. The lint trap in a dryer, for example, is about M 2.

It’s easier for filters with an M value of 5 to 8 to get rid of smaller debris of dust. Smaller particles have a greater chance of getting stuck in your lungs. In order to help keep people and their homes safe from airborne particles, this type of air filter will come into play.

Particle Size Ranges

RangeSize in micronsGroup
10.30 to 0.40E1
20.40 to 0.55
30.55 to 0.70
40.70 to 1.00
51.00 to 1 30E2
61.30 to 1.60
71.60 to 2.20
82.20 to 3.00
93.00 to 4.00E3
104.00 to 5.50
115.50 to 7.00
127.00 to 10.00

Filters with an M rating of 9 to 12 can be used in most homes. They get rid of most of the dust in homes and places of work: They also let cool air pass, making them perfect for recirculating air into hot rooms. Their prices are often reasonable and can fit into a wide range of budgets.

Filters with an M rating of 13 to 16 are thought to be significantly better than the previous ratings. Due to their smaller pores, they need special blowers to recirculate clean air throughout a room. It’s very important not to use these filters in a home’s air conditioner or heater. They are usually used for high-end business applications.

Filters with M ratings of 17 to 20 are no longer available as a new filter type has rendered them obsolete. While this level of filtration efficiency is displayed on the chart, you cannot find such a filter in today’s market. In the past, M 17 to 20 filters were known to capture most dust, viruses, and hazardous materials.

Blue Air Air Purifier

Composite Average Particle Size, % in size Range

MERV Value0.3 – 1.01.0 – 3.03.0 – 10.0Arrestance

How Does MERV Compare to HEPA?

High Efficiency Particulate Air (HEPA) is a mechanical filter that must remove 99.97%of particles 0.3 microns in size. As shown, HEPA filters outperform MERV 0.3-1-micron particle size filters by a significant margin.

The great thing about HEPA filters is that they’re not just for factories. Many modern air purifiers have HEPA filters to trap common allergens like pollen and dander. Homeowners claim that purchasing a HEPA air purifier significantly improved their quality of life.

Air Recommended Air Purifiers

Our Pick Perfect for bedrooms, playrooms, and living rooms, the Coway Airmega AP-1512HH is one of the best-performing, most durable, and most economical purifiers we’ve tested.

Most Popular The Levoit Core 300 air purifier has some strong suits, but in our opinion it falls short of carving out a meaningful niche for itself. Its ideal use would be in a small bedroom occupied by someone who is sensitive to noise.

Also Great With high end air cleaning performance and a whisper quiet fan, the Winix 5500-2 is the perfect combination of power and finesse. It cleared airborne particulates out of our smokey testing room faster than any other model.

Best of the Best If you have a large space you want to remove irritants from, We recommend the Airmega 400S. All of Coway air purifiers do an excellent job of attacking indoor pollutants, and we highly recommend any of them. The 400S is designed to accommodate large room sizes.

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If you have any questions or comments, please add them below in the comment section. Similarly, please let us know if you spot any mistakes or omissions. Thanks!

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About the author

Hi I’m Alex, founder of HouseholdMe.com and I’d like to say thank you for dropping by. Like most of you, the first thing I look at before buying something online is reviews or buying guides. By reading what other people say will help me gauge whether or not a product is good or not.  I am trying to help people find answers, solve problems, and get inspired.

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