What Does MERV, MPR & FPR Mean?

Air filters are rated by several different metrics and systems, depending on a variety of factors. Second Nature makes filters easy by breaking these ratings down and utilizing one standardized metric-MERV.

What is a MERV rating?

MERV ratings were established by the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) in order to aid consumers understanding of what type of air filter will best fit their home’s needs.

MERV is the worldwide standard rating system for air filter quality. The MERV, or Minimum Efficiency Reporting Value, tells the consumer how effectively a filter can catch household contaminants such as dust, pollen, and pet dander. The higher the MERV rating (anywhere from 1 to 16), the more and smaller particles are filtered from the air.

MERV Ratings. Typical Applications

1-4 Residential Window Units
5-8 Better residential, commercial & industrial
9-12 Superior residential, better commercial, hospital labs
13-16 Hospital, general surgery

It is important to keep in mind that MERV indicates the minimum ability of a filter to catch airborne particles. Over time, a filter begins to fill with dust and dander, therefore increasing its ability to stop contaminants from passing through. However, the higher the MERV, and the more a filter has already caught, the harder it becomes for your system to draw in air. A high MERV rating may seem like a good idea to a homeowner who wants to ensure they are breathing fresh air, but it is important to make sure that your HVAC system is capable of handling the restrictive properties of a high MERV filter. Home air filters with higher MERV ratings also need to be changed at a higher frequency due to their higher efficiency and particle-catching abilities. Simply put, they catch more contaminates over a shorter period of time.


FPR, or Filter Performance Rating was developed by the Home Depot, based on independent lab test results comparing MERV ratings. It is used strictly in Home Depot stores and does not correlate directly to MERV ratings.


MPR, or Microparticle Performance Rating, was created by 3M to rank their filters’ ability to catch the smallest airborne particles. MPR is helpful when comparing one 3M Filtrete filter to another, but it does not directly translate to MERV.

MPR vs. MERV vs. FPR

The chart below shows the associated values for each of Second Nature's filter types.

Essential MERV 8 MPR 600 FPR 5
Essential+ MERV 10 MPR 1000* FPR 7*
Health Shield MERV 13 MPR 1500 - MPR 1900 FPR 10

*approximate values

Alec Lower

Content Writer

Alec is a third-year member of the team at Second Nature. He brings expert knowledge of a myriad of home air filtration topics including HVAC filters, filtration efficiency, and indoor air quality.