Guides / Heating and cooling · Updated
MERV rating chart
From EPA's indoor air quality pages and Guide to Air Cleaners in the Home, checked November 2026.
Short answer
MERV rates how well a furnace or AC filter catches particles from 0.3 to 10 microns, on a scale of 1 to 16. EPA suggests at least MERV 13, or as high as your system fan and filter slot can take; MERV 13 catches at least half of the smallest particles tested.
What each rating captures
| MERV | 0.3 to 1 µm | 1 to 3 µm | 3 to 10 µm |
|---|---|---|---|
| 1 to 4 | — | — | under 20% |
| 5 | — | — | 20%+ |
| 6 | — | — | 35%+ |
| 7 | — | — | 50%+ |
| 8 | — | 20%+ | 70%+ |
| 9 | — | 35%+ | 75%+ |
| 10 | — | 50%+ | 80%+ |
| 11 | 20%+ | 65%+ | 85%+ |
| 12 | 35%+ | 80%+ | 90%+ |
| 13 | 50%+ | 85%+ | 90%+ |
| 14 | 75%+ | 90%+ | 95%+ |
| 15 | 85%+ | 90%+ | 95%+ |
| 16 | 95%+ | 95%+ | 95%+ |
Minimum average capture by particle size, from EPA. Smoke and many bacteria sit in the 0.3 to 1 µm column; pollen and dust mite debris in the larger ones.
Can my system take MERV 13?
EPA's guide: "Most furnaces and HVAC systems can accommodate a MERV 13 filter without creating equipment problems, provided that the filter is replaced frequently." Makers typically recommend replacing it every 60 to 90 days. If airflow drops or the system struggles, check the equipment manual for the highest rating it allows. HEPA filters are rated differently (99.97% at 0.3 µm) and don't fit most home systems.
Replacing the system? See what a new one costs and what a higher SEER2 saves.