What is the MERV Rating for Furnace Filters?

MERV stands for Minimum Efficiency Reporting Value and is a scale from 1 to 16 that indicates how well a filter traps small particles, such as dust, pollen, mold, and other irritants. The MERV rating of your filter will tell you how effective it is at keeping these particles out of your home. Generally, the recommended MERV rating for furnace filters ranges from 6 to 8, providing a great balance between maximum furnace efficiency and home comfort. Filter technology has advanced significantly over the years, and MERV ratings are designed to help us choose the most effective and efficient air filter options for heating and cooling systems.

The higher the MERV index, the fewer particles and other contaminants can enter your home. E1, E2, and E3 particles are particle range sizes used to test air filters to determine the MERV rating. Some air filters, especially those with higher MERV values, can reduce air flow due to improved air filtration. Filter King's filter selection tool allows you to select the size, thickness, and MERV rating you need.

A higher MERV rating may mean slightly more restricted airflow; however, most current HVAC systems are capable of handling a MERV 11 air filter without increasing system voltage. MERV 13 air filters even provide additional filtration power against fine particles compared to MERV 11 filters. Activities such as renovating the home, leaving outside doors open, and having children play in the house can accelerate the accumulation of dust and particles in the air filter. If an air filter can capture at least 20% of E1 particles, 65% of E2 particles, and 85% of E3 particles, it will receive a MERV 11 rating.

While MERV ratings reflect a filter's ability to trap microscopic and macroscopic particles, MPR ratings only rate a filter based on its ability to remove particles from 0.3 to 1 micron. In these cases, a MERV 11 air filter can provide additional benefits and capture a wider range of particles that would pass through a MERV 8 filter. Although slightly more expensive than lower rated filters (just a few dollars), using a MERV 11 filter can improve indoor air quality and help relieve people with respiratory problems. Every time you use your furnace or boiler, the air filter will become dirty as dust and particles flow through the system and accumulate in the filter.