The Home Depot Air Filter Performance Rating System (FPR) ranks all brands of filters The Home Depot sells by measuring their ability to capture large and small particles. It also factors in the weight gain caused by the filtration process over the filter’s lifetime. 

The FPR creates a weighted average for each filter, which is then ranked on a 1-10 scale: 1 being the lowest performance and 10 being the highest performance air filter. 

Sixty percent of the rating is determined by the filter's ability to capture large particles, thirty percent is determined by its ability to capture small particles, and weight gain over the filter's lifetime determines the final ten percent.

Premium Air Filters: FPR 10 filter out:

• Particles like household dust, lint, dust mites, pollen and pet dander
• Small particles like bacteria and mold spores
• Smoke, smog, microscopic allergens plus particles that can carry viruses
• Particles that carry odors

Best Air Filters: FPR 9 filter out:

• Large particles like household dust, lint, dust mites, pollen and pet dander
• Small particles like bacteria and mold spores
• Smoke, smog, microscopic allergens plus particles that can carry viruses

Better Air Filters: FPR 7 filter out:

• Large particles like household dust, lint, dust mites, pollen and pet dander
• Small particles like bacteria and mold spores

Good Air Filters: FPR 4 filter out:

• Large particles like household dust, lint, dust mites, pollen and pet dander 

In addition to the filter's strength, the FPR also indicates which type of airborne contaminants each filter is ideally suited to capture.

Contaminants captured by FPR 10, 9, 7, 4 ratings:   

• Dust/Lint                                                                                 
• Pet dander 
• Dust mite 
• Pollen

Contaminants captured by FPR 10, 9, 7 ratings:

• Bacteria 
• Mold 

Tip: Use electrostatically charged air filters for best filtration of these contaminants.

Contaminants captured by FPR 10, 9 ratings:

• Microscopic allergens 
• Smog 
• Smoke 
• Virus carriers 

Tip: Use electrostatically charged air filters for best filtration of these contaminants.

Contaminants captured by FPR 10 ratings:

• Odor 

Tip: Use electrostatically charged air filters for best filtration of these contaminants.

Fiberglass, polyester, washable, pleated and electrostatic filters each offer different air filtering capabilities. Electrostatic filters provide the highest level of filtration for small particles.  

Tip: While most filters are disposable, some may be cleaned with water or by vacuum. One advantage of using disposable filters is that you’re not exposed to trapped contaminants during cleaning. 

Filter Type: Polyester or Fiberglass Air Filters

• Inexpensive
• Disposable
• Good for capturing large particles like lint and dust

Filter Type: Washable Air Filters

• Can be cleaned and reused
• Require replacement only every few years
• Protect furnace motor and trap larger particle

Filter Type: Pleated Air Filters

• Disposable
• Larger surface area captures more particles

Filter Type: Electrostatic

• Disposable or reusable options available
• Charged fibers help to capture small and large particles
• Larger surface area captures more particles

Filters are sized in two ways: nominal and actual. Nominal is the approximate size of the filter, rounded up to the nearest inch. Actual is the filter’s exact size.   

In addition to standard height and width dimensions, air filters also vary by thickness. They can be less than one inch thick or up to six inches thick.

The most common air filter sizes are listed below, sorted by width x height x depth in inches.

• 16 x 25 x 1
• 20 x 25 x 1
• 20 x 20 x 1
• 16 x 20 x 1
• 20 x 25 x 5

Getting an exact fit is crucial to having an effective air filter - the wrong size won't fit and will cause the filter to stop working properly. To ensure you get the right fit, take your current air filter out and check the size printed on the frame. And if you need a custom sized filter, The Home Depot has you covered. We also offer an air filter subsciption. Check out some air filters that are air filter subscription eligible. 

While The Home Depot uses FPR, the industry standard is to use the air filter rating system of Minimum Efficiency Reporting Value (MERV). The MERV rating system helps you choose the filter right for you, with each rating dictating the effectiveness of a filter. The higher the MERV rating, the more efficient the filter, and the more a filter can catch harmful pollutants. 

The American Society of Heating, Refrigeration and Air Conditioner Engineers (ASHARE) recommends a MERV 6 or higher. Most people go with a MERV 8 filter. Most residential areas can remove contaminants with MERV 8 to 13, while most hospitals use MERV 14 to 20.

Compared to The Home Depot’s method of ranking air filters (FPR), MERV has wider range. While FPR’s rating system goes from 1 to 10, MERV’s rating system goes from 1 to 20. FPR 10 is similar in strength to MERV 20, since they are both the highest rating value. However, FPR 1 doesn’t necessarily equate to MERV 1. It isn’t until FPR 4 and 5 that filters start trapping larger particles like household dust and lint, dust mites, pollen and pet dander. Meanwhile, MERV 1 to 4 will trap all these pollutants. Some examples of MERV below:

• MERV 1-4: pollen, dust mites, standing dust, spray paint dust and carpet fibers

• MERV 5-8: mold spores, hair spray, dust mites, animal dander and cement dust

• MERV 9-12: humidifier dust, lead dust, auto emissions and milled flour

• MERV 13-16: household dust and pollen, pet dander, outdoor pollution, mold spores, microscopic allergens, bacteria, most tobacco smoke, sneeze bacteria and virus carriers