Filter size is an important factor in maintaining clean air quality and maximum efficiency in your home’s furnace and air conditioning systems. If the air filter is too small, dust and other contaminants will flow around the filter and enter your home. If it’s too big, well, it simply won’t fit at all—and you’ll be left with unfiltered air until you can get a properly sized filter. At Remember The Filter, you can get standard and custom filters in the exact size you need, including 20x20x1 furnace filters. We even offer free shipping on all orders, which is especially helpful when you need to stock up on 20x20x1 air filters in bulk. Our selection features quality AAF Flanders filters, including Naturalaire and EZ Flow, in both fiberglass and pleated configurations. Browse our selection of 20x20x1 furnace filters today to find the right solution for your home’s air filtration system.