Nominal vs Actual Air Filter Size: Why Both Measurements Matter
Air filters are often sold using nominal sizes such as 12x24x1, while the actual dimensions may be slightly smaller.
Check the Existing Filter
A 12x24x1 filter might actually measure around 11.5 x 23.5 x 0.75 inches depending on the product.
Why the Difference Matters
A filter that is too large may not fit the slot, while one that is too small may not sit properly.
Measure Before Ordering
Check the label on the current filter and measure the actual frame when necessary.
Conclusion
Always compare nominal size + actual dimensions + filter-slot size before purchasing replacements.