The MERV rating, or Minimum Efficiency Reporting Value, is a measurement used to categorize HVAC air filters. It measures how well the filter can capture particles of different sizes. As you shop for air filters for your heating and air conditioning system, you’ll need to understand what the ratings mean and which is right for your needs.

How the Rating System Works

Each filter is given a rating between one and 20. The higher the rating, the higher level of filtration it provides, meaning it’s more capable of capturing smaller airborne particles.

These particles are sized in microns, and smaller microns result in smaller particles. The most common household airborne pollutants are between 3 and 10 microns, including dust, pollen, mold, and bacteria. Some ultrafine particles—as small as 1 micron—include smoke and haze.

Ratings that are under 4 mean that less than 20% of the particles between 3 and 10 microns in size will be captured. A filter rated at 6 will capture almost 50% of them, while an 8 will capture almost 85% of them. A rating of 10 indicates the filter will catch at least 50% of the smaller particles between 1 and 3 microns.

Filters with a rating of 14 will capture 84% of particles 1 to 3, and at least 90% of particles sized 3 and larger. Anything with a rating of 16 will capture 75% or more of the ultrafine particles.

Which to Choose

It may seem that the largest MERV rating is the best air filter to purchase, but using one with too high of a rating will impact the efficiency of your heating and air conditioning system. The higher-rated filters have smaller pores for the air to pass through, forcing the system to work harder to circulate air through them. Most households work well with a filter between 5 and 8, which captures most of the common pollutants. Households that have someone with a respiratory condition, such as asthma or allergies, may prefer a rating between 9 and 12 to capture more of those irritants for the sensitive family members.

The fully certified contractors at Service Air Eastern Shore can help you find the right filters for your system in Silverhill, AL. In addition to air filters, they offer a full array of heating and air conditioning services. Every heat and air repair comes with a three-year labor warranty for your peace of mind. Visit their website for more information and schedule an appointment by calling (251) 990-8060.