What is a MERV Air Filter Rating?
When shopping for a replacement air filter for your home’s furnace, you may have noticed an important detail on its packaging: a MERV rating. Just like any other rating system, the MERV rating can be a crucial determining factor to what type of air filter you buy, and it can be a useful comparison tool while shopping around. Before you buy, learn what a MERV rating is and how it contributes to your home or business’s indoor air quality.
What is a MERV Rating?
“MERV” stands for “Minimum Efficiency Reporting Values” and is a rating system used to inform consumers about an air filter’s ability to capture large particles between 0.3 and 10 microns in diameter. These particles can be contaminants, allergens and other pollutants that get trapped within an interior space and can contribute to poor indoor air quality (IAQ) and even health issues. In order to diminish or remove these particles, an appropriate air filter must be chosen, hence the MERV rating.
The MERV Rating Scale
MERV ratings work on a numerical scale from 1-16; the higher the number, the more efficient the filter is at trapping particles. Additionally, the greater variety in size and amount of contaminants an air filter can trap, the better. When you use an air filter with a higher MERV rating, this means that your air filter has the capability of catching large and small pollutants like mold, pollen, dust and more, which can greatly improve your IAQ.
According to the EPA and the National Air Filtration Association, the MERV rating scale breaks down as follows:
- Filters with a MERV rating of 1-4 can trap less than 20% of particles 3.0-10.0 microns large
- Filters with a MERV rating of 6 can trap around 50% of particles between 3.0-10.0 microns large
- Filters with a MERV rating of 8 can trap around 85% of particles between 3.0-10.0 microns large
- Filters with a MERV rating of 10 can trap around 50%-65% of particles 1.0-3.0 microns large, and 85% or more of microns 3.0-10.0 microns large
- Filters with a MERV rating of 11 can trap around 85% of particles 3.0-10.0 microns large, 65% of particles 1.0-3.0, and 20% of particles 0.3-1.0 microns large
- Filters with a MERV rating of 12 can trap around 80%-90% of particles 1.0-3.0 microns large, and 90% or more of 3.0-10.0 microns large
- Filters with a MERV rating of 13 can trap around 90% of particles 3.0-10.0 microns large, 85% of particles 1.0-3.0, and 50% of particles 0.3-1.0 microns large
- Filters with a MERV rating of 14 can trap around 75%-84% of particles 0.3-1.0 microns large, and 90% or more of microns 1.0-3.0 microns large
- Filters with a MERV rating of 16 can trap around 75% or more of particles 0.3-1.0 microns large
What MERV Rating Should I Choose?
Most residential homes can benefit from an air filter with a MERV rating between 5 and 13, depending on the amount of allergens and pollutants needed to be trapped within your home. For more optimal IAQ benefits, you can narrow down that rating range to within 8-13.
To further determine what MERV rating to choose for your air filter, think about who lives in your space and your furnace or HVAC system: Can your system accommodate that filter type? What’s recommended by your system’s manufacturer? Do you have any pets? Do you live with someone who is affected by allergens? In most cases, a filter with a MERV 8 rating will be perfectly accommodating to your IAQ needs. However, if your home has individuals who have allergies, choose a filter with a MERV 10 to MERV 13 rating.
Commercial and healthcare facilities will require the use of filters with the highest MERV rating, around the 16 to even 20 range. This provides these spaces the best and healthiest IAQ.
For more information about improving your space’s indoor air quality and other shopping tips, check out our post about CADR ratings for air purifiers and our guide of the different types of air purifiers.