Furnace Filter MERV Rating Comparison
Compare furnace filter MERV ratings and their filtration capabilities.
See what each rating filters and which is best for your needs.
Select a MERV rating to see what it filters and whether it is suitable for your system.
Understanding MERV Filter Ratings
MERV stands for Minimum Efficiency Reporting Value, a rating system developed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) in 1987. MERV ratings range from 1 to 20, with higher numbers indicating finer filtration. The rating measures a filter’s ability to capture particles of specific sizes from the air passing through it. Choosing the right MERV rating balances air quality with airflow restriction and system compatibility.
MERV Rating Comparison Chart:
| MERV | Particle Size Filtered | What It Catches | Typical Use |
|---|---|---|---|
| 1 - 4 | Over 10 microns | Pollen, dust mites, carpet fibers | Minimal filtration, protects equipment |
| 5 - 8 | 3 - 10 microns | Mold spores, pet dander, dust | Standard residential (most common) |
| 9 - 12 | 1 - 3 microns | Fine dust, legionella, auto emissions | Better residential, commercial offices |
| 13 - 16 | 0.3 - 1 microns | Bacteria, tobacco smoke, sneeze droplets | Hospitals, general surgery, clean rooms |
| 17 - 20 | Under 0.3 microns | Viruses, carbon dust, sea salt | Pharmaceutical, electronics manufacturing |
Filtration Efficiency by MERV:
| MERV Rating | Efficiency (3-10 microns) | Efficiency (1-3 microns) | Efficiency (0.3-1 microns) |
|---|---|---|---|
| MERV 6 | 35 - 50% | Less than 20% | N/A |
| MERV 8 | 70 - 85% | Less than 20% | N/A |
| MERV 11 | Over 85% | 65 - 80% | N/A |
| MERV 13 | Over 90% | Over 85% | Less than 75% |
| MERV 16 | Over 95% | Over 95% | Over 95% |
MERV vs. FPR vs. MPR:
Different retailers use different rating systems. Home Depot uses FPR (Filter Performance Rating) on a scale of 4 to 10. 3M uses MPR (Microparticle Performance Rating) on a scale of 300 to 2800. Here is a rough comparison:
- MERV 6 = FPR 4 = MPR 300: Basic filtration
- MERV 8 = FPR 5 = MPR 600: Good residential
- MERV 11 = FPR 7 = MPR 1000-1200: Better residential
- MERV 13 = FPR 10 = MPR 1500-1900: Superior residential
- MERV 16 = N/A = MPR 2800: Hospital grade
Airflow Restriction Warning:
Higher MERV ratings mean denser filter media, which restricts airflow through the HVAC system. Most residential furnaces and air handlers are designed for MERV 8 to MERV 11 filters. Using a MERV 13 or higher filter without verifying system compatibility can reduce airflow below acceptable levels, causing the evaporator coil to freeze, the blower motor to overheat, and energy consumption to increase by 5 to 10 percent. Always check your system manual or consult an HVAC technician before upgrading beyond MERV 11.
Filter Replacement Schedule:
| Filter Type | Thickness | Replacement Interval |
|---|---|---|
| Fiberglass (MERV 1-4) | 1 in (25 mm) | Every 30 days |
| Pleated (MERV 5-8) | 1 in (25 mm) | Every 60-90 days |
| Pleated (MERV 9-12) | 1 in (25 mm) | Every 60-90 days |
| Deep pleated (MERV 11-13) | 4-5 in (100-125 mm) | Every 6-12 months |
| HEPA (MERV 17+) | Varies | Per manufacturer specs |
Homes with pets, smokers, or allergy sufferers should replace filters more frequently. Check the filter monthly and replace it when visibly dirty, regardless of the time interval listed above.