Actual vs. Nominal Size (The Size Of Your Air Filter)
When looking to replace your air filter, there are typically two different sizes you need to understand – Actual Size and Nominal Size.
Actual Size consisting of the true dimensions of your filter when measuring length, width and thickness, and typically includes a fraction of an inch. For example: 19 1/2 x 19 1/2 x 3/4
What you might not realize is that filters are not sold by their actual dimensions. Instead a rounded up number is used to label filter packages. This measurement is referred to as the "Nominal Size".
So a filter with:
- Actual Dimension of 19 1/2 x 19 1/2 x 3/4
- Will have a Nominal Size of 20 x 20 x 1
- Nominal Size is the measurement to look for when buying your replacement filters
|20 x 20 x 1|
|19 1/2 x 19 1/2 x 3/4|
|16 x 25 x 1|
|15 1/2 x 24 1/2 x 3/4|
Want to know more? Learn what a MERV Rating is.
- Need to Replace Your Air Filter? -
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