What Does MERV Rating Mean?

MERV stands for Minimum Efficiency Reporting Value which commonly means “I’ll tell you how effective your air filter is”.

Through MERV Rating, you can easily judge the efficiency of your air filters in trapping airborne particles. The higher the MERV, the fewer contaminants get into the air you breathe.

Air Filter MERV Descriptions

MERV 1 to 4. Pollen, dust and carpet fibers can be trapped using air filters with MERV 1-4. They have less than 20% efficiency in trapping these particles.

MERV 5-8. Aside from pollens and dust, filters with MERV 5-8 can strain mold spores, dust from cement, and allergens between 3 and 10 microns at 30-70% efficiency.

MERV 9-12. Air filters can trap lead dust, pet dander, milled flour and allergens ranging from 1 and 10 microns. They yield from 85-90% particulate efficiency.

MERV 13-16. With 90% and above filter efficiency, they can trap bacteria, tobacco smokes and airborne particles at less than 1 micron in size. You can typically find these air filters in hospitals.

Is higher MERV rating always the right choice?

Looking back at the MERV descriptions above, you may think that higher MERV rating is always a good choice but no. Filters with higher MERV rating have smaller pores and may cause restriction in airflows. This can affect unit performance and stress the fan of your system.

Before you purchase an air filter, a short research would be helpful. Be sure that the MERV rating of your air filter is compatible to your system. The last thing that you want to have is high energy cost and inefficient unit.

What is the ideal MERV rating?

With extra research, you can answer this question yourself. Just make sure that your system and the air filter you intend to buy are in harmony with each other. For typical household, air filters with MERV 8-13 is a good choice.

Air filters should be replaced at least twice a year but if you have filters with higher MERV rating, you might want to replace them every 3 months or more often. Since they have small pores, trapped particles may block the airflow and can cause pressure on your system.

For best performance, pair up your air filter with regular maintenance. No matter how high the MERV rating of your air filter is, if it’s not properly maintained, it will still do you no good.