What is MERV?

Minimum Efficiency Reporting Value

Commonly known as a MERV rating, this measurement scale, designed in 1987 by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), was created to rate the effectiveness and efficiency of air filters. The scale represents a quantum leap in the precision and accuracy of air-cleaner ratings' and allows for improved health, reduced cost and energy efficiency in heating, ventilation and air conditioning (HVAC) design.

The scale is designed to represent the worst-case performance of a filter when dealing with particles in the range of 0.3 to 10 micrometers. The MERV rating is from 1 to 20. Higher MERV ratings correspond to a greater percentage of particles captured on each pass, with a MERV 16 filter capturing more than 95% of particles over the full range.

MERV 1–4 | 10.0 μm Pollen, dust mites, cockroach debris, sanding dust, spray paint dust, textile fibers, carpet fibers.

Residential window AC unit.

MERV 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

MERV 9–12 | 3.0–1.0 μm Legionella, Humidifier dust, Lead dust, Milled flour, Auto emission particulates, Nebulizer droplets.

Better. Residential, better commercial, hospital laboratories

MERV 13–16 | 1.0–0.3 μm Bacteria, droplet nuclei (sneeze), cooking oil, most smoke and insecticide dust, most face powder, most paint pigments.

Best. Hospital & general surgery

MERV 17–20 | < 0.3 μm Virus, carbon dust, sea salt.

Superior. Smoke electronics & pharmaceutical manufacturing cleanroom