What Is a MERV Rating and Why Does It Matter?

With so many air purifiers and filters on the market, it can be difficult to know which one is right for your home or business. MERV ratings use a numerical scale to provide consumers with an objective measure of a filter’s efficiency to help them make an informed decision.

Minimum Efficiency Reporting Value (MERV) ratings compare the efficiency of a filter against the particle size it can capture. Originally designed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), MERV ratings score filters on a scale from 1 to 20. The higher the MERV rating, the better that filter will be at removing small particles from the air.

While a high MERV rating indicates a better quality air-filter, consumers should evaluate these scores based on their particular needs. Filters with high MERV scores have smaller pores, for example, which will put more strain on your HVAC system and require more energy to operate. ASHRAE recommends MERV 13 and 14 but if your system cannot accommodate these filters, you should choose one with the highest rating possible.

Most homes can maintain good quality air using a filter with a MERV rating between 7 and 13. MERV 5 through MERV 8 filters are considered medium quality and are generally sufficient for removing mold and dust from the air. Individuals with allergies or other chronic respiratory conditions should consider filters with a rating of MERV 9 or higher to better protect against pollen, dander and other harmful particles.

These guidelines also apply to businesses, although your choice of filter should reflect the type of business you operate. Filters with a MERV rating of 16 or higher typically require commercial HVAC systems and are highly effective at removing extremely fine particles from the air. Hospitals, industrial facilities, laboratories and other specialized workplaces may benefit from using one of these filters.

Whichever filter you choose, it is important for consumers to be informed about the product’s capabilities and limitations. Be sure to check the MERV rating before purchasing your next air-filter to help ensure you are using the one that best suits your needs.