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What does MERV or MERV Rating mean?

Your filters MERV Rating is a good way to help judge the effectiveness of the filter. MERV means Minimum Efficiency Reporting Value which was developed by the American Society of Heating, Refrigeration and Air Conditioner Engineers - ASHRAE. MERV values vary from 1 to 16. The higher the MERV value is the value the more efficient the filter will be in trapping airborne particles. Another consideration is air flow through the your HVAC system. Leaving a dirty air filter in place or using a filter that is too restrictive may result in low air flow and possibly cause the system to malfunction.

ASHRAE recommends MERV 6 or higher
US Department of Energy recommends MERV 13
LEED recommends MERV 8 at a minimum.

See the chart below for filter MERV descriptions.


Minimum Efficiency Reporting Values - MERV ratings

 

MERV Value
The filter will trap
Average Particle
Size Effiency
0.3 - 1.0 Microns
The filter will trap
Average Particle
Size Effiency
1.0 - 3.0 Microns
The filter will trap
Average Particle
Size Effiency
3 - 10 Microns
Types of things
these filters
will trap
MERV 1
  -  - Less than 20%
 Pollen, Dust mites,
Standing Dust,
Spray Paint Dust,
Carpet Fibers
MERV 2
  -  - Less than 20%
MERV 3
  -  - Less than 20%
MERV 4
  -  - Less than 20%
MERV 5
  -  -  20% - 34%
 Mold Spores,
Hair Spray,
Fabric Protector,
Cement dust
MERV 6
  -  -  35% - 49%
MERV 7
  -  -  50% - 69%
MERV 8
  -  -  70% - 85%
MERV 9
  -  Less than 50%
 85% or better Humidifier Dust,
Lead Dust,
Auto Emissions,
Milled Flour
MERV 10  -  50% - 64%
 85% or better
MERV 11 - 65% - 79%
 85% or better
MERV 12 - 80% - 89%
 90% or better
MERV 13 Less than 75%
 90% or better
 90% or better Bacteria,
Most Tobacco
Smoke,
Proplet Nuceli (sneeze)
MERV 14 75% - 84%
 90% or better 90% or better
MERV 15 85% - 94%
 90% or better 90% or better
MERV 16 95% or better 90% or better 90% or better

Shopping for Air conditioner filters or humidifier water panels.