A MERV Rating (Minimum Efficiency Reporting Value) is a measure of a furnace air filter worst-case efficiency performance. It is a 1-20 scale. 1 being the lowest compares to air passing through a spiders web and 20 being the highest compares to air hitting brick wall. The higher the MERV Rating the better the air furnaces filters will clean your air. However, in most cases anything higher than a MERV 13 and your furnace will not be able to pull air through it. Anything less than a MERV 6 does close to nothing at cleaning the air that passes through it.

Most systems installed in homes are designed to operate using an air furnace filter with a MERV rating of no higher than 13. Any higher than that, and you risk burning out your motor. An air conditioning filter rated higher than a MERV 13 requires a special system built to move air through that dense of a filter. If replaced regularly, filters with a MERV rating of 8 to 13 will be sufficient to provide all the benefits of clean air and improved efficiency.

Below is an air furnace filter chart with the most common MERV rated filters and what they will clean out of the air.

MERV Rating             MERV 6    MERV 8     MERV 11     MERV 12     MERV 13
UL Listed Class 2           X                X                 X                  X                   X
Electrostatic Charged    X                X                 X                  X                   X
Antimicrobial                  X                X                 X                  X                   X
Large Lint & Dust      X                X                 X                  X                   X
Pollen                                                X                 X                  X                   X
Dust Mite & Debris                      X                 X                  X                   X
Mold Spores                                      X                 X                  X                   X
Smoke                                                                  X                  X                   X
Auto Emissions                                                  X                  X                   X
Pet Dander                                                            X                  X                   X
Bacteria                                                                                    X                   X
Viruses                                                                                      X                   X
Air-born Allergens                                                                                     X