What is a MERV Rating?
MERV Rating is the Minimum Efficiency Reporting Value for air conditioner furnace filter media as determined by the American Society of Heating, Refrigerating, and Air Conditioning Engineers, ASHRAE. MERV is the primary international air conditioner furnace filter industry standard and is used for rating the ability of a furnace filter to capture and hold particles and pollutants. The measurement used in these ratings is a Micrometer, or micron.
- A micron is one millionth of a meter (0.000001m) and is not visible to the human eye.
- A piece of copy paper is about 100 microns.
- A human hair averages 80 microns in size.
- Pet dander is 2-4 microns and can linger in the air for hours before it settles on a surface!
Most residential systems are well able to use up to MERV 12. Below is a table grouping MERV ratings by particle size:
|MERV||Min. particle size||Typical controlled contaminant||Typical Application|
|1–4||> 10.0 µm||Pollen, dust mites, cockroach debris, sanding dust, spray paint dust, textile fibers, carpet fibers||Residential window AC units|
|5–8||10.0–3.0 µm||Mold, spores, dust mite debris, cat and dog dander, hair spray, fabric protector, dusting aids, pudding mix||Better residential, general commercial, industrial workspaces|
|9–12||3.0–1.0 µm||Legionella, Humidifier dust, Lead dust, Milled flour, Auto emission particulates, Nebulizer droplets||Superior residential, better commercial, hospital laboratories|
|13–16||1.0–0.3 µm||Bacteria, droplet nuclei (sneeze), cooking oil, most smoke and insecticide dust, most face powder, most paint pigments||hospital & general surgery|
|17–20||< 0.3 µm||Virus, carbon dust, sea salt, smoke||Electronics & pharmaceutical manufacturing cleanroom|
For filter sizes and MERV options go to Air Filters.