Furnace Filter Sizes

There are hundreds, if not thousands, of different furnace filter sizes in the market today. PureFilters carries over 900 different filter sizes, and even if you don't see your furnace filter size listed on our website, we manufacture custom sizes as well.

The size of your furnace filter will largely depend on your furnace, AC, HVAC unit or other filter intake tray. The easiest way to find out what your furnace filter size is by simply inspecting your furnace filter.

Below are all of our filter size categories, organized by thickness:

1 Inch Furnace Filters

1 inch furnace filters are by far the most common thickness. They are used in both residential and commercial furnaces, air conditioners, duct systems and HVAC units.

Below are the 5 most common 1 inch furnace filter sizes

16x25x1

20x20x1

20x25x1

16x20x1

14x20x1 

View all 1 inch furnace filters

2 Inch Furnace Filters

2 inch furnace filters are far more common in commercial and industrial settings. However there are a few residential HVAC units/systems that have a 2 inch filter intake as well.

Below are the 5 most common 2 inch furnace filter sizes

20x20x2

16x25x2

16x20x2

20x25x2

24x24x2

View all 2 inch furnace filters

3 Inch Furnace Filters

3 inch furnace filters are very rare and are used almost exclusively in residential settings. PureFilters only carries a handful of branded OEM 3 inch furnace filters.

View all 3 inch furnace filters

4 Inch Furnace Filters

4 inch filters are found in residential, commercial and industrial environments. There are several branded OEM filters that are 4 inch thick as well, PureFilters manufactures our own line of 4 inch furnace filters.

Below are the 5 most common 4 inch furnace filter sizes

16x25x4

20x25x4

20x20x4

16x20x4

24x24x4

View all 4 inch furnace filters

5 Inch Furnace Filters

5 inch furnace filters are almost exclusively used in residential environments. There are some rare circumstances where a commercial or industrial building uses a 5 inch furnace filter, but as mentioned, it is quite rare.

Below are the 3 most common 5 inch furnace filter sizes

16x25x5

20x25x5

20x20x5

View all 5 inch furnace filters

6 Inch Furnace Filters

6 inch furnace filters are almost exclusively used in residential environments. There are some rare circumstances where a commercial or industrial building uses a 6 inch furnace filter, but as mentioned, it is quite rare.

Below are the 3 most common 6 inch furnace filter sizes

16x25x6

20x25x6

20x20x6

View all 6 inch furnace filters

Often times filter may have two measurements listed on it, one of called the "nominal size" and the other is the "actual size" or "exact size. It is important to know the difference between these two measurements, which is why we wrote a Guide on Furnace Filter Sizes

Another way to fund out what your furnace filter size is would be to just measure it with a tape.

Once you know your nominal and exact furnace filter size, find it listed below.

Below are furnace filters sizes categorized by their NOMINAL SIZE in ascending thickness. The thickness of your filter is the last number of the nominal size. For example, for 16x25x1 the thickness is 1 inch and for 20x20x2 the thickness is 2 inch. 

Here is a picture of a filter being measured, thickness being the 3rd image:

 

Request Custom Filters

If you still cannot find your furnace filter listed on our store, you can always request a custom size filter. Custom size filters can take up to 15 business days to deliver and all custom size filter sales are final (no refunds/exchanges). In order to request a custom size filter and receive a quote for your order, please click on the link below.

Request custom size filter

If you need help finding your exact filter on PureFilters.ca and prefer to speak to someone, please give us a call at 1-888-979-4284 or email us at support@purefilters.ca. We are available Monday to Friday from 9AM to 5PM Eastern Standard Time.