What is a MERV rating?

MERV rates a filters ability to capture and filter out unwanted airborne particles.

A higher number means the filter is capable of filtering out more unwanted particles, as well as smaller particles.

Fit is important

Choosing an air filter of the appropriate size is very important. Installing an air filter of the wrong size can drastically reduce the effectiveness of filtration or the hardware utilizing the filters.

To find the correct size for your application, check your furnace or air conditioner for a tag or sticker indicating the recommended air filter size. If you are unable to locate such a tag, remove your existing filter and look for a set of three measurements on the outer frame of the filter. These labels will contain three measurements: The length, width and depth (for example: 16 x 24 x 1).

Once you know the appropriate filter size for your application, simply enter your measurements into our Air Filter Finder to find the air filters you need.

Filters size can be listed in two waysâ€"nominal and actual. Typically, filters are labelled with their nominal sizing - which is the approximate size of the filter, rounded up to the nearest whole inch (example 16 x 14 x 4). Nominal size is sometimes also called the advertised size. The actual size is the exact size of the filter (example 15 ¾ x 13 ½ x 3 ¾).

Change your filters frequently

Air filters come with a recommended replacement frequency, which is commonly every 3 months. If you follow the manufacturer's recommendations, you can reduce the chance of your filter becoming clogged with particles. A clogged filter greatly reduces filtration efficiency. A clogged filter also restricts airflow, increasing pressure on the fan side, which can put unnecessary strain on your air conditioner or furnace. This can also reduce the airflow rate in your house, which can negatively impact the air quality in your home.

Higher MERV ratings are not always better

A filter with too high of a MERV rating can negatively impact flow rate in your ventilation system. Less flow means less overall recirculation, which may negatively affect your home's air quality.

We recommend verifying the suggested air filter size and MERV range of your application before purchasing air filters.

MERV, MPR and FPR Rating Systems Explained

Have you wondered why there are 3 different rating systems? Certain brands have created their own rating system but, at the end of the day, they are rating the same filter! Unaware consumers often find themselves paying premium prices at grocery stores or big box retailers. Learn the facts and your next purchase will be much easier on your wallet.

MERV (Minimum Efficiency Reporting Value) is the primary rating system used in the industry, both domestically and internationally.

MPR (Micro-Particle Performance Rating) is a rating system developed by 3M.

FPR (Filter Performance Rating) is a rating system developed by The Home Depot for brands sold through their stores, including Honeywell.

This chart illustrates how the ratings compare to one other:

MERV Rating comparison chart

MERV	MPR	FPR	Packaging color
6	300	N/A	White
8	600	4 - 5	Green
11	1000	6 - 7	Red
12 - 13	1500+	8 - 10	Blue/Black