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The Simple Guide to MERV

How It Works

What are MERV Ratings?

MERV (Minimum Efficiency Reporting Value) is the industry-standard ratings system used to measure the effectiveness of air conditioner filters. Ratings for residential and commercial AC filters typically fall between MERV 5 and MERV 12. Filters with higher MERV ratings remove more particles and allergens than lower-rated filters.  

The MERV system was developed in 1987 by the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE), the international trade group that represents HVAC professionals.

Why is MERV important?

Studies show that central air filtration is the best way to improve indoor air quality. MERV ratings determine how effective that filtration is. Good indoor air quality reduces the symptoms of asthma and allergies, especially in children. For more information on indoor air quality, please check out our air quality guide.

What MERV Rating is Right for Me?

The American Lung Association recommends using at least a MERV 8 filter. People who suffer from asthma and allergies should use a higher quality MERV filter, at least MERV 11.

On Time Air Filters subscribers can select one of 3 quality levels:

  • Better - On Time Air Filters Better quality level filters are rated MERV 8. Filters rated from MERV 5 to MERV 8 are categorized as Better Residential filters. Filters in this range pick up most of the dust, debris, mold and pet dander in your home or office. This is the minimum quality level that we recommend to our customers and do not sell filters rated below MERV 8.
  • Best - Our Best filters are rated MERV 11. Superior Residential filters are rated between MERV 9 and MERV 12, and will pick up a larger amount of dust and allergens. We highly recommend these filters for any customers who have asthma, allergies and any other respiratory condition.
  • Best for Pets - These filters are made with Activated Charcoal, which is proven to eliminate odors, especially chronic household ones let smells left by pets and tobacco smoke. Our Best for Pets filters are rated MERV 8.

Why Not Go Higher?

Filters with very high MERV ratings (MERV 13+) are designed for specialized commercial uses (hospitals, clean rooms, etc.). These filters restrict air flow so much that they use substantially more electricity and can damage your air conditioner or furnace unit.  If you want a higher level of filtration, consider buying a portable air cleaner that uses a HEPA or MERV 16 filter, in conjunction with MERV 11 A/C and furnace filters.

What About FPR and MPR Ratings?

FPR and MPR are proprietary ratings systems developed by home improvement stores and filter manufacturers.  They are not directly relatable to MERV (an FPR 4 filter cannot be compared to a MERV 4 filter).  These ratings systems are not endorsed or backed by ASHRAE, and we do not recommend using filters not rated under the MERV system.

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