MERV Rating Chart: What Every Level From 1 to 16 Means
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MERV ratings run from 1 to 16, and each step means a filter catches more particles in a lab test. The chart below shows the minimum each level must capture, what that looks like in a real building, and how to read it when you are standing in front of a wall of filters.
What MERV measures
MERV stands for Minimum Efficiency Reporting Value. It comes from ASHRAE Standard 52.2, which tests a filter against particles in three size ranges:
- E1, 0.3 to 1 micron: smoke, combustion particles and other very fine particles
- E2, 1 to 3 microns: fine dust and smaller allergen fragments
- E3, 3 to 10 microns: pollen, dust mite debris, mold spores and larger dust
A filter's MERV is the highest level whose minimums it meets in all three ranges. Higher numbers catch smaller particles.
MERV rating chart
| MERV | E1 (0.3 to 1 µm) | E2 (1 to 3 µm) | E3 (3 to 10 µm) | Typical use |
|---|---|---|---|---|
| 1 to 4 | None | None | Under 20% | Basic fiberglass and window unit filters; rated mainly on catching large debris |
| 5 | None | None | 20% or more | Most homes; light commercial prefilters |
| 6 | None | None | 35% or more | |
| 7 | None | None | 50% or more | |
| 8 | None | None | 70% or more | |
| 9 | None | 35% or more | 75% or more | Better residential; general commercial buildings |
| 10 | None | 50% or more | 80% or more | |
| 11 | None | 65% or more | 85% or more | |
| 12 | None | 80% or more | 90% or more | |
| 13 | 50% or more | 85% or more | 90% or more | Commercial and institutional buildings; EPA's suggested minimum for wildfire smoke where the system allows |
| 14 | 75% or more | 90% or more | 95% or more | |
| 15 | 85% or more | 90% or more | 95% or more | |
| 16 | 95% or more | 95% or more | 95% or more |
Minimum composite efficiencies from ANSI/ASHRAE Standard 52.2-2017, Table 12-1. "None" means the standard sets no minimum for that range at that level.
How to read the chart
The big jumps are at 9 and 13. MERV 5 through 8 only have to catch the largest range. MERV 9 is the first level with a minimum for 1 to 3 micron particles, and MERV 13 is the first with one for particles under 1 micron, which is where smoke sits.
Higher MERV costs airflow. Catching smaller particles takes denser media, and denser media makes your blower work harder. A rating your system was not designed for can cut airflow, lengthen run times and strain the blower. Your furnace or air handler manual lists what it can handle. We cover this trade-off in detail in MERV 8 vs MERV 11.
Most homes run MERV 6 to 8. That range handles everyday dust, pollen and pet dander without much airflow penalty in a standard 1 inch slot.
MERV, MPR and FPR are not the same
Some retail brands print their own scales, such as MPR or FPR, instead of or next to MERV. Those are brand ratings from different tests and do not convert exactly to MERV. If you want to compare filters across brands, look for the MERV number.
HEPA is also separate. HEPA filters are tested to a different standard and sit above the MERV scale. They are common in portable air cleaners but rarely fit a home HVAC system without modification.
Which EverFilter products sit where
- EverFilter Washable MERV 6: washable MERV 6 media in a reusable aluminum frame. Rinse and reuse.
- EverFilter Starter Kit and Refill Packs: MERV 8 media pads in a reusable aluminum frame. Replace the pad, keep the frame.
- EverFilter Electrostatic Washable: a washable, layered electrostatic filter for everyday dust, pollen and pet dander. It is not sold with a MERV rating. How electrostatic filters work.
- Commercial filters: MERV 11 to MERV 15 deep-bed filters (rigid cell, V-bank, bag and mini-pleat) for commercial air handlers and rooftop units.
None of our residential filters are built for smoke. If that is your concern, the EPA suggests MERV 13 or higher where your system allows, or a HEPA air cleaner.
Common questions
What MERV rating should I use at home?
Start with what your HVAC manufacturer recommends. For most homes with a 1 inch filter, MERV 6 to 8 is the sweet spot. Step up only if you have a reason and your system is rated for it.
Is a higher MERV always better?
Only if your system can move air through it. A MERV 13 filter in a system built for MERV 8 can do more harm than good.
Does MERV change as a filter gets dirty?
The rating is a lab result on a new filter. In use, a loading filter catches more but also restricts more airflow, which is why changing or cleaning on schedule matters.
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Sources: U.S. EPA, What is a MERV rating?; ANSI/ASHRAE Standard 52.2-2017, Table 12-1; U.S. EPA, Guide to Air Cleaners in the Home; U.S. EPA, Wildfires and Indoor Air Quality.