MERV Ratings Explained: What Each Number Means for Your Furnace Filter
MERV ratings explained: the ASHRAE 52.2 scale from 1 to 16, EPA's table of capture by particle size, why EPA suggests MERV 13, and how MERV compares with HEPA.
Affiliate disclosure: product links on this page go to Amazon, or to the maker's own store for brands that sell only direct. As an Amazon Associate we earn from qualifying purchases, at no extra cost to you; a link to a maker's store earns us nothing. No retailer or brand sees our picks before they are published or has any say in them. How we choose.
MERV, the Minimum Efficiency Reporting Value, is a 1 to 16 score for how well an HVAC filter captures particles between 0.3 and 10 microns, from a test method developed by ASHRAE (Standard 52.2). The higher the number, the more particles it catches in each size band. EPA advises choosing at least MERV 13, or as high as your system fan and filter slot can accommodate, and consulting an HVAC technician to be sure.
MERV 13 means the filter captures, on average, at least 50% of 0.3 to 1 micron particles, 85% of 1 to 3 microns and 90% of 3 to 10 microns. MERV 8, a common basic filter, has no minimum for the smallest band. The full table is below.
The MERV table
| 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% |
What the size bands mean
- 3 to 10 microns: larger dust, pollen, mold spores and pet dander. Even MERV 8 catches at least 70%.
- 1 to 3 microns: finer dust and some bacteria-size particles. Capture rises sharply from MERV 8 (20%) to MERV 11 (65%).
- 0.3 to 1 micron: smoke, combustion particles and the finest dust, the range most relevant to PM2.5. Only MERV 11 and up have a minimum here. See PM2.5 explained.
Why EPA suggests MERV 13
EPA's guide to air cleaners recommends that anyone concerned about small particles choose at least MERV 13, which requires at least 50% removal of 0.3 to 1 micron particles. EPA's technical summary goes further: because central systems run only part of the time, some MERV 12 and most MERV 13 to 16 filters are likely to be almost as effective as HEPA filters at reducing indoor particle concentrations. EPA's guidance on respiratory viruses also points to MERV 13 or the highest the system can handle.
The catch: your system has to handle it
EPA's technical summary says not all HVAC fans can accommodate high-efficiency filters without reducing airflow to the point where heating or cooling capacity is lost, which can cause comfort problems and component failure. Resistance generally, but not necessarily, rises with MERV: deeper pleating, thicker filters and electrostatically charged media can deliver higher MERV with low resistance. If in doubt, EPA suggests consulting an HVAC technician, who can measure static pressure. See whether a MERV 13 upgrade is worth it.
Filter types by MERV
| Type | Typical MERV | Notes |
|---|---|---|
| Flat or panel (fiberglass and similar) | 1 to 4 | Mainly protects equipment; about 1 to 2 in thick |
| Pleated, extended surface | 5 to 13 or higher | Most common upgrade; efficiency varies even at the same MERV |
| High-efficiency pleated or deep media | 14 to 16 | Higher resistance unless deeply pleated |
| HEPA (home products) | Comparable to MERV 16 | Rated separately; no widely accepted consumer definition |
MERV vs HEPA
EPA says HEPA filters are not rated on the MERV scale; they are rated at 99.97% efficiency for 0.3 micron particles. HEPA filters are common in portable air cleaners, while MERV ratings are the way to compare furnace and central HVAC filters. See True HEPA vs HEPA and HEPA bypass systems.
MERV vs MPR and FPR
EPA notes that MPR and FPR are proprietary ratings. MPR is 3M's scale for Filtrete filters, and Filtrete's own listings pair MPR 1000 with MERV 11, MPR 1500 with MERV 12 and MPR 1900 with MERV 13. FPR is The Home Depot's scale. Compare filters by MERV where the brand gives it. See MERV vs MPR vs FPR.
Choosing your MERV
- MERV 13 if your system handles it: EPA's suggested minimum for fine particles.
- MERV 11 or 12 if MERV 13 reduces airflow, or for allergies where large particles matter most.
- MERV 8 for rentals, construction dust or very restrictive systems.
- MERV 14 to 16 only in deep media cabinets or with a technician's check.
For picks, see the best HVAC filters and MERV 8 vs 11 vs 13.
Frequently asked questions
What does MERV stand for?
Minimum Efficiency Reporting Value, a 1 to 16 rating from a test method developed by ASHRAE that reports how well a filter captures particles between 0.3 and 10 microns.
What MERV rating is best for a home?
EPA advises at least MERV 13, or as high as your system fan and filter slot can accommodate. Consult an HVAC technician if you are unsure.
What does a MERV 13 filter catch?
At least 50% of 0.3 to 1 micron particles, 85% of 1 to 3 microns and 90% of 3 to 10 microns, on average, according to EPA's MERV table.
Is a higher MERV always better?
For capture, yes. But EPA says some systems cannot handle the extra airflow resistance, which can reduce capacity and cause comfort or equipment problems.
Is MERV 16 the same as HEPA?
EPA says HEPA-designated home filters usually perform comparably to MERV 16, but HEPA is rated separately, at 99.97% for 0.3 micron particles, and has no widely accepted consumer definition.
Is a MERV 8 filter good enough?
It catches at least 70% of 3 to 10 micron particles, so it handles dust and pollen, but EPA's table sets no minimum for the smallest particles at MERV 8.
Sources
- What is a MERV rating?, US Environmental Protection Agency
- Guide to Air Cleaners in the Home, US Environmental Protection Agency
- Residential Air Cleaners: A Technical Summary (3rd edition), US Environmental Protection Agency
- Air Cleaners, HVAC Filters, and Coronavirus (COVID-19), US Environmental Protection Agency
Related guides
Are Washable HVAC Filters Worth It? The Trade-Offs in Numbers
Washable filters save waste but most are MERV 8, which catches large dust and pollen and little smoke-size particulate. For allergies or smoke, a disposable MERV 13 is the better buy.
Best HVAC Filters for Allergies: MERV 12 and 13 Picks
Pollen, dust mite debris and dander are mostly large particles, which MERV 12 and 13 filters catch at 90% or more. Our top allergy pick is the Filtrete MPR 1500 (MERV 12).
Best HVAC Filters of 2026: MERV 13 and Alternatives for Every System
EPA suggests MERV 13 or the highest your system can handle. Our top pick is the Filtrete MPR 1900, a MERV 13 1-inch filter; here are five more for different systems and budgets.