What Size House Filter Do I Need? A Comprehensive Guide

Air filter sizes can be intimidating, especially when many homes have several filters of different sizes. But don't worry, Second Nature is here to make buying filters easy. Once you enter your filter sizes with us just once, not only do you not have to remember when it's time to change them, but you'll no longer need to remember those complicated sizes. The first step in finding the right size air filter is to measure the length and width (L x W).

If the filter is not a square, the smallest measurement comes first. Most air filters have their size printed on the side of the frame. The length, width and depth of the filter are measured in inches. For example, you'll say something like “16x25x1”, where 16 is the length, 25 is the width, and 1 is the depth. It's important to note that different brands may have slightly different sizes for the same filter.

For example, Home Depot primarily sells Honeywell brand air filters, while ACE Hardware primarily sells Filtrete. If the filter is too large, it won't fit in the filter slot and you won't be able to replace the cover. However, you can choose not to use factory-installed filter grids and have an HVAC professional install an external filter grid for a thicker filter. Once you've determined the exact dimensions that best suit your needs, order the filter size with the exact fraction or decimal of your preferred measurements. There are many options for buying air filters with convenience, either a) online, b) through your HVAC service company, or c) in-store. If the dimensions are too discolored to read or there's no air filter to look at, it's time to measure it yourself.

You'll need to do this if your boiler is missing the air filter and you don't know what size the air filter is supposed to be. The size of the pleated air filter is always presented in a chain of three numbers, where the first number represents the length, the second number represents the width and the last number represents the thickness. Finding the right size air filter doesn't have to be a daunting task. With Second Nature's easy-to-use system, you can quickly find and order exactly what you need without having to worry about complicated measurements or confusing brands.