The easiest way to determine your filter size is to look for the dimensions printed directly on the filter frame.
Most filters, whether they are for HVAC systems, air purifiers, or other appliances, have the dimensions clearly marked on their frame. You'll typically find two sizes listed:
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Nominal Size: This is a rounded-off, simplified dimension often printed in a larger font. It's used for general reference and ease of selection.
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Actual Size: This is the precise measurement of the filter, usually printed in a smaller font. This is the most accurate dimension to consider when replacing a filter.
Therefore, to know your filter size, simply locate and read the printed label on your current filter frame. The label will clearly indicate the filter's length (L), width (W), and depth (D) in inches, typically written as L x W x D. For example, "20 x 25 x 1" or "16 x 20 x 4." Be sure to use the actual size when purchasing a replacement.
