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 |
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