MERV rating chart
MERV rates how well an air filter captures particles from 0.3 to 10 microns, on a scale of 1 to 16. The higher the number, the more small particles it traps, on the EPA's 2026 MERV chart below.
The EPA MERV chart
| Rating | 0.3–1.0 µm | 1.0–3.0 µm | 3.0–10.0 µm |
|---|---|---|---|
| MERV 1–4 | none | none | under 20% |
| MERV 5 | none | none | ≥ 20% |
| MERV 6 | none | none | ≥ 35% |
| MERV 7 | none | none | ≥ 50% |
| MERV 8 | none | ≥ 20% | ≥ 70% |
| MERV 9 | none | ≥ 35% | ≥ 75% |
| MERV 10 | none | ≥ 50% | ≥ 80% |
| MERV 11 | ≥ 20% | ≥ 65% | ≥ 85% |
| MERV 12 | ≥ 35% | ≥ 80% | ≥ 90% |
| MERV 13 | ≥ 50% | ≥ 85% | ≥ 90% |
| MERV 14 | ≥ 75% | ≥ 90% | ≥ 95% |
| MERV 15 | ≥ 85% | ≥ 90% | ≥ 95% |
| MERV 16 | ≥ 95% | ≥ 95% | ≥ 95% |
MERV 8 vs 11 vs 13
MERV 8 has no minimum below 1 micron. MERV 11 must capture at least 20% of particles from 0.3 to 1.0 microns, and MERV 13 at least 50%.
| Particle size | MERV 8 | MERV 11 | MERV 13 |
|---|---|---|---|
| 0.3–1.0 µm | none | ≥ 20% | ≥ 50% |
| 1.0–3.0 µm | ≥ 20% | ≥ 65% | ≥ 85% |
| 3.0–10.0 µm | ≥ 70% | ≥ 85% | ≥ 90% |
An EPA bulletin for new homes says: “Filters with a MERV of 11 remove roughly 20% of the particles between .3 and 1 micron, and a MERV 13 filter typically demonstrates at least 50% removal efficiency for the smallest particles tested”. The same bulletin says Indoor airPLUS, the EPA's program for new homes, requires filters of at least MERV 8.
Trane calls 8, 11 and 13 the common MERV ratings. Its filter guide says MERV 8 “effectively filters down to 3-10 microns”, MERV 11 to 1-3 microns and MERV 13 to .3-1 microns.
How the ASHRAE 52.2 test sets the number
- The test counts particles in front of and behind the filter at twelve particle sizes, grouped into three ranges: E1 (0.3–1.0 µm), E2 (1.0–3.0 µm) and E3 (3.0–10.0 µm).
- The MERV is a single number: the highest row of the chart whose minimums the filter meets in all three ranges.
- NAFA's summary of ANSI/ASHRAE Standard 52.2 lists the same E1, E2 and E3 minimums as the EPA chart for MERV 5 to 16.
HEPA filters use a separate scale
The EPA lists HEPA filters at 99.97% or more of 0.30 µm particles, and says this figure is not based on the MERV rating system. HEPA filters are common in portable air cleaners.
Fiberglass filters rate 1 to 4
The EPA says “a typical 1-inch-thick spun fiberglass furnace filter has a rating of 1 to 4 on the MERV scale”. Trane says pleated filters carry higher MERV ratings than generic fiberglass filters.
Other scales on filter packs
The EPA notes that “some filters may be graded by their manufacturers on alternative proprietary scales”. MERV is the scale set by the ASHRAE 52.2 test, so it is the number to compare across brands.
MERV 13, choosing a rating and AprilAire filters
| Page | What you get |
|---|---|
| MERV 13 filters | What MERV 13 captures, and the MERV 13 filters makers list with size and life |
| What MERV rating to use | The MERV options each cabinet maker lists |
| AprilAire filters by model | Which AprilAire filter fits each air purifier, with its MERV |
Sources
- EPA, What is a MERV rating? (page updated 2026-01-14): https://www.epa.gov/indoor-air-quality-iaq/what-merv-rating, accessed 2026-10-28
- EPA, Indoor airPLUS Technical Bulletin: Filtration, EPA 402/B-20/006 (2020, PDF): https://www.epa.gov/sites/default/files/2020-06/documents/2019.11_tech_bulletin_filtration.pdf, accessed 2026-10-28
- Trane, Furnace Filter Guide (updated 2025-09-08): https://www.trane.com/residential/en/resources/troubleshooting/gas-furnaces/furnace-filter-guide/, accessed 2026-10-28
- NAFA, Understanding ANSI/ASHRAE Standard 52.2 (January 2026, PDF), Tables 2 and 3: https://www.nafahq.org/assets/pdf/522BrochureJanuary2026/, accessed 2026-10-28