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Furnace and A/C Filter Sizes

Make the switch to a brand that has been trusted since 1950. All filters are manufactured in the US by AAF Flanders, the largest air filter manufacturer in the country. AAF Flanders filters are selected for their quality and value by organizations that require the cleanest air possible, including NASA and hospitals. Not all filters are created equal.

 

Common Sizes

10x10x1
10x20x1
10x24x1
12x12x1
12x20x1
12x24x1
12x25x1
12x30x1
14x14x1
14x20x1
14x24x1
14x25x1
14x30x1
15x20x1
16x16x1
16x20x1

16x24x1
16x25x1
16x30x1
16-1/2x21-1/2x1
18x18x1
18x20x1
18x24x1
18x25x1
20x20x1
20x24x1
20x25x1
20x30x1
22x22x1
24x24x1
24x30x1
25x25x1
10x20x2
12x20x2
12x24x2
14x20x2
14x25x2
15x20x2
16x16x2
16x20x2
16x24x2
16x25x2
16x30x2
18x20x2
18x24x2
18x25x2
20x20x2
20x24x2
20x25x2
24x24x2
25x25x2

 

12x24x4
16x20x4
16x25x4
18x24x4
20x20x4
20x25x4
24x24x4


Where is my filter located?

Your filter can be located anywhere between the furnace and the where warm or cool air enters the room. Common locations include inside the ductwork, behind vents or in the air handler itself.

What size filter do I need?

Most furnace filters have two sets of dimensions; nominal and actual. If you measure your filter and it's actually 15 1/2" x 24 3/4" x 3/4", you would round up and search based on the nominal dimensions of 16" x 25" x 1". If the nominal size isn't printed on your old filter just measure your filter width, length and thickness. Round up and you'll get the nominal size. We always recommend measuring your filter just to be sure.