Understanding The MERV Rating For Your Air Filter

Posted on: 2 July 2020


There are a variety of air filters on the market ranging from pleated filters, washable ones, and even activated charcoal-infused disposable filters. However, one of the most important qualities is the MERV rating, which measures how well your filter can do it's job.

Minimum Efficiency Reporting Value

The MERV of a filter, or the Minimum Efficiency Reporting Value, is a filter's ability to block particles .3 to 10 microns (one millionth of a meter) in size at it's worst. The different MERV values represent different percentages of those sized particles that the filter can block. For example, a filter with a MERV rating of 1 can block less than 20% of all .3-10 micron particles, while a MERV 8 filter blocks nearly 85%.

The MERV rating can also change depending on the type of filters. For example, disposable filters typically have a MERV rating between one and eight. Pleated filters typically are better at filtering than your average disposable air filter and therefore tend to have higher MERV values. The folds in the filter allow for more surface area for the air to filter through, which means more particles are caught. Electro-static filters, or washable filters, are typically made to last forever but don't filter as well as other models. Additionally, if you are looking for the maximum air filtration, there are HEPA filters available that trap 99% of all particles. These higher-end models are more commonly used in large facilities such as hospitals and factories, as they can handle an equally heavy-duty AC unit that's needed.

A Harder Job for Your AC Unit

The higher the MERV rating on your filter, the worse the airflow is for your AC unit. Higher MERV rated filters trap more particles and therefore need to not only be cleaned more often but prevent more and more air from flowing through your system. This means that your air conditioner will have to work harder to do the same job. This is frequently a waste of energy over time unless you are incredibly good at cleaning and replacing your air filter. Plus, it can cause leaks in the system if the airflow is blocked too much. Most air filters sold don't go above MERV 12, and it's generally considered okay to use MERV 8 rated filters if you want to. You absolutely do not need a MERV 16 rated filter, even for those with allergies and asthma.

MERV ratings show the consumer the ability of the given air filter to block out tiny particles present in the air. The higher the MERV rating, the fewer particles float through the air, but your AC unit will have to work harder. Avoid buying air filters rated above MERV 12 as those rated between 8 and 12 are perfectly fine for most households.