Written by: Will Housh
Indoor Air Quality Expert and President of DiscountFurnaceFilter.com

What Is MERV?

The MERV (Minimum Efficiency Reporting Value) rating of a filter describes the size of the holes in the filter that allow air to pass through. The higher the MERV rating, the smaller the holes in the filter, the higher the efficiency.

Recently the American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) and the air filter industry have come up with a standardized rating system, based on the European concept, of a MERV rating for each type of air filter. This numbering system makes it easier to evaluate and compare mechanical air filters and will hopefully eliminate some of the confusion regarding the overall effectiveness of any type of a mechanical air filter on removing airborne particulates, especially those that are less than 2 microns in size.

COMPARING VARIOUS AIR FILTERS TO MERV RATINGS

Throw-Away Fiberglass Media MERV 1 -MERV 4
Pleated Media Air Filters 30% ASHRAE MERV 10 - MERV 11
Pleated Media Air Filters 65% ASHRAE MERV 13 *
(* 65% ASHRAE is about 20% effective on less than 1 micron particles)
Pleated Media Air Filters 95% ASHRAE MERV 14

Some of the man-made synthetic media like that used in the 3M Filtrete air filters may be rated MERV 15. However, they hold very little dust and load up quickly and have a relatively high-pressure drop (static pressure) and can affect the performance of the heating/cooling system.
If you need any more information or have any questions as you consider an indoor air quality purchase, please do not hesitate to contact our customer support team via email by clicking here: I Have A MERV Question

As always, Thank You for shopping at DiscountFurnaceFilter.com. We sincerely appreciate your business.

Will Housh
Founder and President
DiscountFurnaceFilter.com