Definition for word: MERV. Minimum Efficiency Reporting Value

A rating assigned to HVAC air filters that describes how efficient they are at trapping airborne dust and other particulate matter. MERV 1-4 traps particles 10 microns and larger. MERV 5-8 can trap 3-10 micron particles, and MERV 9-12 can trap particles as small as 1 micron.

Referrence from

Minimum Efficiency Reporting Value, commonly known as MERV Rating is a measurement scale designed in 1987 by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) to rate the effectiveness of air filters.

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 micrometres. The MERV rating is from 1 to 16. 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.

Below is a table of example MERV ratings:

MERV       Min. Particle Size      Example Application

20           < 0.3 um                Cleanroom

16           0.3-1.0 um             General Surgery

12           1.0-3.0 um             Superior Residential

8            3.0-10.0 um            General Commercial

4            > 10.0 um               Minimal Filtration

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