What does MERV stand for?

Minimum Efficiency Reporting Value. It is a grade from 1 to 16 under ASHRAE Standard 52.2 that reports how well a filter captures particles from 0.3 to 10 microns. The higher the number, the more of the smaller particles the filter captures.

Is MERV 16 the same as HEPA?

No. MERV 16 requires 95% or more in each of the three particle-size groups from 0.3 to 10 microns. A HEPA filter captures 99.97% or more of 0.3-micron particles, and HEPA ratings are not part of the MERV scale.

What does 95% mean on a bag or box filter?

It is the maker's efficiency figure for the filter, not a MERV. Where we know both, the listing shows them together: our 95% bag filters are rated MERV 14 or 15, our 95% box filters MERV 14, and our 65% bag filters MERV 11.

Is a higher MERV always better?

A higher MERV captures more of the smallest particles, but it only helps if the filter fits your unit. Choose from the filters listed for your machine; where two grades fit the same slot, pick by the dust or fume you are collecting.

What MERV are your cartridge filters?

80/20 cartridges are MERV 11 or 12 and spunbond polyester cartridges MERV 11. Nanofiber cartridges are MERV 14 or 15, UltraLife cartridges MERV 15, and the genuine Airflow Systems CLEAN-2, FIBERDUST and ULTRACLEAN-PLUS cartridges MERV 14 where rated. Each listing states its MERV.

MERV Ratings Explained

What the ASHRAE 52.2 MERV grade measures, what each grade from MERV 8 to 16 captures, and how MERV compares with the percentage and HEPA ratings on our filters.Updated November 14, 2026

What a MERV rating means

MERV stands for Minimum Efficiency Reporting Value. It is a grade from 1 to 16 set by ASHRAE Standard 52.2, the test method for general ventilation filters, and it reports how well a filter captures particles between 0.3 and 10 microns (µm). The higher the MERV, the more of the smaller particles the filter captures.

The test sorts particles into three size groups:

E1: 0.3 to 1.0 µm, the smallest particles.
E2: 1.0 to 3.0 µm.
E3: 3.0 to 10.0 µm.

Particle counts are taken upstream and downstream of the filter when it is clean and again after five rounds of loading it with test dust. For each size range, the lowest efficiency of the six readings is the one that counts, so a MERV is a worst-case figure rather than a best one.

What each grade requires

These are the minimum capture efficiencies for MERV 8 to 16, and where each grade shows up on our listings.

MERV	0.3–1.0 µm (E1)	1.0–3.0 µm (E2)	3.0–10.0 µm (E3)	On our listings
8	—	20% or more	70% or more	Pleated pre-filters
10	—	50% or more	80% or more	Poly pre-filter media
11	20% or more	65% or more	85% or more	80/20 and spunbond polyester cartridges; 65% bag filters
12	35% or more	80% or more	90% or more	One 80/20 cartridge
13	50% or more	85% or more	90% or more	—
14	75% or more	90% or more	95% or more	95% box filters; some nanofiber and the Airflow Systems cartridges
15	85% or more	90% or more	95% or more	Most 95% bag filters; most nanofiber cartridges and all UltraLife cartridges
16	95% or more	95% or more	95% or more	Two 95% DOP filters

Reading the number

The difference is mostly in the smallest particles. Every grade from 11 up captures most of the 3–10 µm range; what changes is the 0.3–1.0 µm group, from 20% at MERV 11 to 75% at MERV 14, 85% at MERV 15 and 95% at MERV 16.
On our cartridges, the media for fine weld fume and smoke (nanofiber, UltraLife) is rated MERV 14–15, and the media for dry, coarser dust (80/20) is MERV 11–12. The filter media guide covers each one.
MERV is not service life. The same test measures how much dust a filter holds, but that figure is not meant to predict how long a filter lasts in use. Change filters by the gauge and airflow: see when to change filters.
Pick within what fits. A higher MERV only helps if the filter fits the slot. Where we list two grades for the same machine, either one fits: the Airflow Systems F120, F240, F360 and F480 air cleaners take a 65% bag as standard and a 95% bag as the option, and many cartridge slots take 80/20 (MERV 11) or nanofiber (MERV 15).

Percentages, HEPA and DOP

Percentages such as 65% or 95% on bag, box and mist filters are the maker's efficiency figure, not a MERV. Where we know both, the listing shows them side by side, such as "95% (MERV 15)". MERV replaced ASHRAE's older dust-spot efficiency test (Standard 52.1), which was removed from the standards in 2009.
HEPA filters are not rated on the MERV scale. A HEPA filter captures 99.97% or more of 0.3 µm particles, and our HEPA filters are listed at 99.97%.
DOP filters on our listings are given as 95% DOP efficiency; two of them are also rated MERV 16.

Sources: US EPA, What is a MERV rating?; National Air Filtration Association, Understanding MERV: User's Guide for ANSI/ASHRAE Standard 52.2.

Frequently asked questions

What does MERV stand for?: Minimum Efficiency Reporting Value. It is a grade from 1 to 16 under ASHRAE Standard 52.2 that reports how well a filter captures particles from 0.3 to 10 microns. The higher the number, the more of the smaller particles the filter captures.
Is MERV 16 the same as HEPA?: No. MERV 16 requires 95% or more in each of the three particle-size groups from 0.3 to 10 microns. A HEPA filter captures 99.97% or more of 0.3-micron particles, and HEPA ratings are not part of the MERV scale.
What does 95% mean on a bag or box filter?: It is the maker's efficiency figure for the filter, not a MERV. Where we know both, the listing shows them together: our 95% bag filters are rated MERV 14 or 15, our 95% box filters MERV 14, and our 65% bag filters MERV 11.
Is a higher MERV always better?: A higher MERV captures more of the smallest particles, but it only helps if the filter fits your unit. Choose from the filters listed for your machine; where two grades fit the same slot, pick by the dust or fume you are collecting.
What MERV are your cartridge filters?: 80/20 cartridges are MERV 11 or 12 and spunbond polyester cartridges MERV 11. Nanofiber cartridges are MERV 14 or 15, UltraLife cartridges MERV 15, and the genuine Airflow Systems CLEAN-2, FIBERDUST and ULTRACLEAN-PLUS cartridges MERV 14 where rated. Each listing states its MERV.