What does MERV Ratings mean to me?

What does a MERV Rating mean to me?

The acronym MERV stands for "Minimum Efficiency Reporting Value." MERV ratings are used to rate the ability of an air cleaner filter to remove dust from the air as it passes through the filter. MERV is a standard used to measure the overall efficiency of a filter. The MERV scale ranges from 1 to 16, and measures a filter's ability to remove particles from .3 to 10 microns in size. To give you an idea of the scale of a micron, 100 microns is about the thickness of a piece of paper or a human hair. Filters with higher ratings not only remove more particles from the air, they also remove smaller particles.

MERV ratings are determined by adding particles of varying sizes into a controlled testing environment. The particles are added upstream of the test filter and a laser particle counter samples the air before it enters the filter and after it leaves the filter. The two particle counts are compared to calculate the Particle Size Efficiency of the tested filter. Once this is determined, a MERV Parameters chart is used to determine the MERV rating.

See the MERV Rating Chart below for more information about the difference in performance between filters with different MERV ratings.

What does a MERV Rating mean to me?

MERV Rating
Dust Spot Efficiency*
Typical Controlled Contaminant
Applications
Air Filter Types
1
<20%
>10 micron Particle Size
 
Pollen, Dust Mites, Sanding Dust, Textile Fibers, Carpet Fibers
Minimal Filtration
Residential
Window A/C Units
Throwaway – Disposable fiberglass or synthetic
Washable – Aluminum
Electrostatic – Self Charging
2
<20%
3
<20%
4
<20%
5
<20%
3-10 micron Particle Size
 
Mold Spores, Hair Spray, Fabric Protector, Dusting Aids, Cement Dust
Commercial Buildings
Better Residential
Industrial Workplace
Paint Booth Inlet
Pleated – Disposable, extended surface area
Throwaway – Disposable synthetic panel
6
<20%
7
25-30%
8
30-35%
9
40-45%
1-3 micron Particle Size
 
Legionella, Humidifier Dust, Lead Dust, Auto Emissions, Welding fumes
Better Commercial
Superior Residential
Hospital Laboratories
Welding Booth Inlet
Bag Filter - synthetic media, typically 6”-36” deep
Box Filter – cartridge, typically 4” deep
10
50-55%
11
60-65%
12
70-75%
13
89-90%
.3-1 micron Particle Size
 
All Bacteria, Most Tobacco Smoke, Proplet Nuceli (Sneeze)
Superior Commercial
General Surgery
Hospital Rooms
Smoking Lounge
Bag Filter - synthetic media, typically 6”-36” deep
Box Filter – cartridge, typically 4” deep
14
90-95%
15
>95%
16
>95%

* Dust spot efficiency measures a filter's ability to remove large particles, those that tend to soil building interiors.