What’s The Difference Between a MERV 8 and a MERV 11 Furnace Filter?

What’s The Difference Between a MERV 8 and a MERV 11 Furnace Filter?

Claudia Pereira21/6/21

When shopping for furnace filters, there are myriad factors that need to be taken into account in order to ensure that it suits your use case scenario perfectly and you get the most value out of the product you purchase. These factors include price, size, brand, and so forth. 

One of the most important amongst these factors is what is known as the MERV rating. At the heart of an optimally functioning HVAC system is a furnace filter with the correct MERV rating for your case. It is, therefore, in every homeowner’s best interest to look into the MERV rating system, what it entails, and which rating would be right for their air filtration needs.

For residential use, choosing a furnace filter with a MERV rating between 7 and 13 is the standard recommendation. For most Canadian homes, furnace filters with MERV ratings in this range suffice in filtering out a good majority of airborne impurities. The most popular choices within this range are MERV 8 and MERV 11 filters. This begs the question—what’s the difference between MERV 8 and MERV 11 furnace filters?

While these two options may appear to be nearly the same, they are, in reality, very different. If you are trying to determine which one is best for your household, here is all that you need to know to settle your doubts and help you decide.


What does MERV Rating Mean?

Before we delve into the difference between specific MERV ratings, let us take a brief look at the meaning of MERV rating and what this rating system entails. MERV is an abbreviation that stands for Minimum Efficiency Reporting Value. It is essentially a widely accepted and used rating system for air filters that makes use of a scale of 1 to 16 to indicate how efficiently, and to what degree, the filter can trap airborne contaminants. 

One on the scale indicates the lowest efficiency while 16 indicates the highest. This means that a furnace filter with a lower rating would hold back a smaller percentage of debris and impurities in comparison to a filter with a higher rating. It’s fundamental to remember that the MERV rating of an air filter denotes its lowest possible capacity, that is, the minimum percentage of impurities that it would be able to effectively filter out.

The MERV rating system thus provides a standard for the comparison of a variety of furnace filters from different manufacturers.


Who Needs a MERV 8 Filter?


  • Furnace filters with a MERV 8 rating are very popular for residential use. This is a well-rounded affordable option that suits a large number of households.
  • A MERV 8 furnace filter usually has a filtration efficiency of a little over 80%. This means that it can effectively filter out about 80% of the contaminants that enter it.
  • Filters with a MERV 8 rating can trap pollen, dust, lint, dust mites, mold, and other large particle impurities.
  • A MERV 8 rated filter can be perfect for your HVAC system if your home is not situated in or around smoke-polluted areas and there are no pets in the family.
  • If you or a member of your family has respiratory issues, or you live in an area with smoke pollution or have a pet, a higher MERV rating would be a better choice.


Who Needs a MERV 11 Filter?


  • MERV 11 rated air filters have a filtration efficiency of a little over 90%, making them highly efficient.
  • MERV 11 furnace filters effectively trap pollen, dust, lint, dust mites, and mold, along with smoke, pet dander, smog, auto emissions, bacteria, and other such fine particles.
  • A MERV 11 filter would be the perfect choice for your home if you or a family member has any form of mild allergy, if your home is located in an area with mild to moderate smoke pollution, or if you are a pet owner.
  • Since MERV 11 filters have a higher efficiency and remove more pollutants they come at a higher price point, but worth it if you have pets and members of your household suffer from allergies.
  • A MERV 11 filter also traps odours, which is ideal for households with smokers or multiple pets.


MERV 8 vs MERV 11—Which is Better?

Now that we have addressed the question ‘what’s the difference between MERV 8 and MERV 11 filters’, let us take a look at which one is actually better for you.

  • While a MERV 11 rated filter traps finer particles, it gets clogged much more quickly in comparison to a MERV 8 filter. Consequently, MERV 11 filters have to be replaced a lot more frequently. You can take a look at our guide on how often you should change your furnace filter for more on this topic.
  • A MERV 8 filter is the more affordable of the two options and is perfect for filtering out large particle impurities. However, for homes situated in heavily polluted areas, or those having one or more pets or a family member with  allergies, a MERV 8 isn’t the best option.
  • MERV 11 filters can effectively trap odours, while MERV 8 filters cannot.


Is a MERV 11 Rating Too High for My Household?


Using a furnace filter with a MERV rating higher than your use case scenario requires can have adverse effects. The thickness of the filter material in a MERV 11 filter, for instance, is more than that of a MERV 8 filter. Therefore, for sufficient air to pass through the filter, a greater amount of energy is consumed. Increased usage can lead to more wear and tear, so make sure to regularly maintain your furnace. MERV 11 filters however, are not considered to be too high for residential use. Anything higher than a MERV 11 is designed for commercial or households with family members suffering from respiratory issues.


Key Takeaways

MERV 8 and MERV 11 filters are significantly different. While these are the two most commonly preferred ratings for home use, it is best to take things into consideration the level of pollution in your city or town, the number of pets in the household, if there are smokers or family members suffering from allergies, before choosing between these two ratings.

If you need help finding the right filter for your household, the PureFilters team is here to help. Feel free to reach out and be sure to place your online order today. 

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