Choosing the Correct Filter Size, and the Filter Type that Fits Your Needs

Before you select an air filter, you need to know which size to buy to fit your HVAC systems. The easiest way to determine this is to look on the old filter currently in your system. You can also find this information in your HVAC owner's manual or manufacturer’s specifications.

Next, make certain the air filter you choose fits the needs of your family based on the level of filtration desired. The Home Depot has developed an Air Filter Performance Rating System to help you select the type of filter that best suits your filtration needs for your home. This comparison tool weights and ranks air filters by their performance to help you easily compare all brands and models of air filters sold by The Home Depot.

The Home Depot Air Filter Performance Rating (FPR) System

The Home Depot Air Filter Performance Rating System, tested by an independent third-party lab, measured all brands of air filters we sell by measuring: 1) ability to capture large particles, 2) ability to capture small particles, 3) and weight gain (filter lifetime). The results of this testing were weighted in a scale as follows:

Large Particle Capture: 60%
Small Particle Capture: 30%
Weight Gain/Lifetime: 10%

The Home Depot Air Filter Performance Rating System created a weighted  average for each filter, which was then ranked on a 1 – 10 scale: one being the lowest performance, and 10 being the highest performance air filter. This scale takes the guess work out of choosing the best air filter for your home, depending on your needs. In addition to the number, rating ranges have been assigned their own color and descriptor: Premium (10) is blue, Best (8-9) is purple, Better (6-7) is red and Good (4-5) is green. This new system makes it simple to compare and select the best air filter for you. High efficiency air filters in particular are a cost-effective way to help improve indoor air quality which may be beneficial to family members sensitive to allergens and other particles that may be found in the air in your home. Air filters also help keep your furnace’s coils and heat exchangers clean which may prolong furnace life and help keep it running efficiently.

Types of Filters

Different types of air filters have different capabilities. Performance is determined by the size and density of the material used, as well as the size and volume of the particles being filtered. Refer to the table below to determine which type of air filter best meets your needs.

Filter Type	Benefits
Fiberglass or Polyester	Inexpensive Disposable Good for capturing large particles like lint and dust
Washable/Reusable*	Can be cleaned and reused Require replacement only every few years Protect furnace motor and trap larger particles
Pleated	Disposable Larger surface area captures more particles
Electrostatic*	Disposable or reusable options Charged fibers help to capture small and large particles

* Filters are most effective when new and clean.

Improve Your Indoor Environment

You can begin improving the air quality in your home immediately just by changing or upgrading your air filter. There are several factors to consider when deciding which air filter to buy.

• The type of air filter you need depends on the presence of airborne particles in your home and the sensitivity of your home’s occupants to those contaminants.

• Some filters need to be changed or cleaned monthly and others only every few months. If someone in your home smokes, you should change your filter more often.

Filter Size

Be sure to purchase the right size filter to match your furnace. Consult the owner’s manual for manufacturer-recommended specifications.

• Filters can be sized in two ways—nominal and actual. Nominal sizing is the approximate size of the filter, rounded up to the nearest whole inch. This makes filter sizes easier to identify when shopping, which is why you’ll find that nominal sizing is most prominent on product packaging. The actual size is the exact size of the filter. 

• Air filters can also vary by thickness. They can be less than one inch thick, or more than 4 inches thick.

• The filter should fit snugly in the chamber; loose filters may let air pass around the filter instead of through it.

Other Factors to Consider

Frames
Sturdiness is an important feature when selecting a filter. The frame should be strong enough to withstand pressure caused by the air that moves through it. Check the frame to see if it is intact and that the joints are secure.

Disposability
While most filters are disposable, some may be cleaned with water or by vacuum. An advantage of disposable filters is you’re not exposed to the trapped contaminants during cleaning.