![actual size for 4 inch air filter actual size for 4 inch air filter](https://5.imimg.com/data5/SELLER/Default/2023/1/XD/PC/PS/144528595/4-inch-air-filter-caliber-500x500.jpg)
There are thousands upon thousands of possible exact air filter sizes that can be used in an HVAC unit.For instance, you may find that the stock size at your local hardware store is just a bit too big to fit your housing slot however, you may be able to find the same stock size online by a different manufacturer that is slightly smaller size and it fits perfectly. Slight variances in size may make a difference in certain situations.This is completely normal and is the standard in air filter manufacturing. For example, a stock size of 20x20x1 may have exact dimensions of 19-1/2 x 19-1/2 x 3/4. The exact size is always slightly smaller than the nominal size to allow the filter to properly fit in the slot or housing. The die-cuts (filter frames) are manufactured in bulk and purchased as a raw material for making air filters and determine the exact size of the air filters. Exact Size: This can vary slightly depending on the manufacturer.
![actual size for 4 inch air filter actual size for 4 inch air filter](https://5.imimg.com/data5/BP/MB/MY-24099829/hydraulic-air-filter.jpg)
All 16x25x1 filters are designed to fit standard 16x25x1 filter slots. Nominal Size: This is the approximate size, such as 16x25x1.We do manufacture and stock them all because that’s our business! So take a look at our stock filters, from the most common 16x20x1, 20x20x1, 16x25x1, 20x25x1 to other sizes like 8x16x1 to 30x36x2 to 25x29x4 to 20x25圆. US Home Filter makes over 80 standard stock sizes that local stores do not have the shelf space for, nor the inventory capacity to keep them in stock. There are only about 10 of the most common air filter sizes available at retail locations.Also, if there is any air flow resistance caused by using a filter that is not correctly sized, it can result in unnecessary stress on the HVAC unit itself, potentially damaging your system equipment and increasing your energy bills. But why is filter size important? According to EPA.gov, incorrectly sized or installed filter frames can cause air seepage, which significantly decreases filter effectiveness. Most AC and HVAC units use standard sized filters, but some do require a custom size air filter to be purchased and installed. Every unit has a specific sized filter which allows the it to perform correctly and efficiently. For example: 16x20x1, 20x20x1, 16x25x1, 20x20x1 are all standard sized air filters. Have you heard the term “Standard stock size” air filter? This merely means that your HVAC unit has a filter that is a common size that is mass produced and easily found.