What is MERV, MPR, FPR Rating?

MERV stands for the Minimum Efficiency Reporting Value for air conditioner furnace filter media as determined by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE).  MERV ratings are internationally standardized to rate the ability of a furnace filter to capture and hold particles and pollutants. Due to the small size of these particles and pollutants, the standard unit of measurement used in these ratings is a Micrometer, or micron.

• A micron is one millionth of a meter (0.000001m) and is not visible to the human eye.
• A piece of copy paper is about 100 microns.
• A human hair averages 80 microns in size.
• Pet dander is 2-4 microns and can linger in the air for hours before it settles on a surface!

While not all filter manufacturers use the MERV rating system, FrequentFilters.com does.  Our AC Furnace Air Filters are manufactured in the USA and have been since 1960. We offer filters in all sizes and all MERV ratings, however, we offer only MERV 8, MERV 10, and MERV 12 online, to help keep things simple for you.

Other companies have developed their own rating systems.  One such rating is the “Microparticle Performance Rating” (MPR) which was developed by a large manufacturer to grade their air filters based on the ability to filter air particles smaller than 1 micron. The MPR is not considered to be the industry standard by ASHRAE.  The published MPR Rating numbering system is a scale of 0 – 2700, with their highest published furnace filter equaling a MERV 13.

Another rating you may encounter is the FPR Rating (Filter Performance Rating).  This grading system uses a color/number system on a scale of 4 (green circle) to 10 (blue circle). Some of the FPR air conditioner filter descriptions refer to the MERV Rating and the MPR Rating, but be careful because the numbers and ratings don’t always agree.

It is important to note that the MERV Rating is the “MINIMUM” initial efficiency rating. It’s the efficiency rating given to the air conditioner furnace filter when it is brand new and is expressed as a percentage of the total airborne particles of a certain size. As the new air conditioner furnace filter traps more debris, it becomes more efficient – trapping the smallest particles as time goes by. Eventually, every air filter will trap the tiniest particles less than 1 micron, until it becomes so dirty that air cannot get through. Air Filter Gages measure the building pressure behind the aging furnace filter and can let you know it’s time to replace the AC Furnace Air Filter.

FrequentFilters.com was created with the purpose of providing our customers with an easy solution to help ensure that your filter is checked and replaced on a timely schedule.  With our products and services, you can rest easy knowing your filters are clean, your AC furnace system is running efficiency, and the overall air quality of your home or business is the best it can be.

FrequentFilters.com AC Furnace Air Filters are available in ½ inch air filters, 1 inch air filters, 2 inch air filters, 4 inch air filters, 5 inch air filters, and 6 inch air filters. Custom size air filters are also available. Contact us if you need a size or MERV rating not listed on our website.

To help naviage the different scales and rating systems, please refer to the chart below.