When it comes to air filters, there are two different sizes that you need to be aware of: the actual size and the nominal size. The actual size is what you would find if you were to use a ruler to measure the exact dimensions of the filter. The nominal size, on the other hand, is the size you see printed on the side of the air filter. It is based on the actual size, which is rounded to the nearest whole inch.
This system ensures that consumers can turn to industry standards and not have to manufacture custom air filters every time they need some clean air. The actual size of the filter is what your exact measurements indicate. You would use a measuring tape to find this. It should fit snugly in the air filter compartment with a little space around the edges.
If it's too large, however, the frame will wrinkle, air flow will be restricted, and longevity will be compromised. On the other hand, if it's too small, it will come loose and some of the air (and debris) won't pass through. When looking for an air filter, you only need to know its nominal size. This is usually printed on the cardboard edge of the filter. But how do you find the perfect air filter? It's a combination of knowing how to measure an air filter accurately and understanding that the dimensions you see may not match up with the actual size.
Most people won't find what they need at their local home improvement store, so they may have to look in their HVAC manual. Since air filters are usually sold for their nominal dimensions, it is essential to learn how to measure them correctly. If the dimensions are too faded to read or there is no air filter to look at, it's time to do it yourself. Measure it yourself and make sure that it fits snugly in its compartment with a little space around the edges. Finding an air filter that fits your needs can be tricky if you don't know what you're looking for. Knowing both your actual size and nominal size, as well as understanding how they differ from each other, can help you make an informed decision when purchasing an air filter.
With this knowledge in hand, you can ensure that your air filter fits perfectly in its compartment and provides clean air for years to come.
