What is the Best MERV Rating for Filters?

Minimum Efficiency Report Value (MERV) ratings are a system designed by ASHRAE (American Society of Heating, Refrigeration, and Air Conditioning Engineers) to measure the effectiveness of air filters. The higher the number, the better the filter is at capturing larger particles between 0.3 and 10 microns (µm). The most common airborne contaminants that these filters are tested against include pollen, dust mites, mold spores, dust, pet dander, bacteria, and tobacco smoke. MERV 17 to MERV 20 filters are commonly used in operating rooms, cleanrooms, and other settings that require absolute cleanliness.

The worst percentage of the six tests is selected as the official measure used to determine the MERV rating of a filter. MERV 11 pleated filters are also made with synthetic media and live up to Merv 8, without a significant price increase. Selecting the right MERV rating for your air filter is a delicate balance between the capabilities of your HVAC system and the indoor air quality you want to have. Using an air filter with a MERV rating higher than recommended by the manufacturer of your oven or air conditioner may impair its performance.

Filters with high MERV ratings can remove more harmful pollutants from your home, but they can actually reduce the quality of the air you breathe if you select a filter with a MERV rating that is too high for your HVAC system. Overall, our recommended MERV rating for oven filters ranges from 6 to 8 to strike a great balance between maximum oven efficiency and home comfort. You can also find the Microparticle Performance Rating (MPR) system, which ranges from 300 to 2200 and measures the effectiveness of a filter in trapping only the smallest particles on the MERV scale (0.3-1 microns in size). No one in this family suffers from a respiratory condition that justifies buying a filter with a higher MERV rating, but every time they have guests, more dirt, dust, and other contaminants enter this house.

Below is a table that can help you determine the recommended MERV rating for a variety of applications.