MERV 11 Vs. MERV 13 Air Filters: What's the Difference?

Furnace filters are an integral part of a well-functioning HVAC system. Not only do they clean and purify the air circulated through your home, but they also remove harmful irritants such as dust, pet dander, pollen and mold. To ensure your HVAC system is functioning properly, it helps to understand the MERV rating system so you can choose the best filter. 

So, what does MERV mean in air filters? The initialism MERV stands for Minimum Efficiency Reporting Value. This rating, which was created in 1987 by the American Society of Heating Refrigerating and Air Conditioning Engineers (ASHRAE), indicates how efficiently a filter can remove particles from the air flowing through an HVAC system. When looking at filter specifications on packaging, you’ll notice a rating from 1 to 20. In short, the higher the rating, the more effective the filter is at removing foreign particles. It’s helpful to keep in mind that a filter’s MERV rating indicates its minimum performance, rather than its maximum performance (which would only be attainable when used in ideal operating conditions).

There’re also other rating systems used to indicate furnace filter performance such as Micro-Particle Performance Rating (MPR) and Filter Performance Rating (FPR). However, the MERV system is the most used and, for the average customer, is the easiest system to understand.

The difference between a MERV 11 filter and a MERV 13 filter is in filtration compacity. Here’s a quick comparison of the two filter types: 

• A MERV 11 filter is the most popular choice for residential homes. This type of filter can remove most of harmful contaminants from a home environment, including smoke, dust mites, pet dander, mold, pollen, dust and smog. MERV 11 filters can remove around 90% of foreign particles found in air. 

• A MERV 13 filter can remove all the same types of particles from the air as a MERV 11 filter with the addition of also removing some viruses and bacteria. MERV 13 filters can remove around 98% of the particles found in air, which can make a significant difference for severe allergy sufferers, for those who live in heavily polluted areas, or for those who are immunocompromised themselves or live in a household with individuals who are susceptible to viral and bacterial infections.

When it comes to air filters, is MERV 13 too high for residential homes? Are MERV 11 filters better suited? MERV 11 and MERV 13 filters are designed to remove smaller particles than other types of filters. This means they create greater resistance as air travels through an HVAC system. While most newer systems can accommodate filters with higher MERV ratings, if you have an older system, a filter with a high MERV rating may lower the air pressure too much, which can interfere with the system’s function or strain the blower.

Whether you have an older or a newer HVAC system, always check the manufacturer’s specifications to see what type of filter it can handle. You can typically find these specifications by checking the owner’s manual or contacting the manufacturer. If you’re unable to determine the specifications for your system, contact an HVAC professional for help.