Furnace filter size index

Each size page covers nominal vs actual dimensions, MERV 8 / 11 / 13 guidance, and buy links. Live pages are highlighted; the rest ship on the nightly queue.

1-inch sizes

20×25×1 16×20×1 16×25×1 20×20×1 14×25×1 14×20×1 16×16×1 12×12×1 12×24×1 14×14×1 15×20×1 16×24×1 18×24×1 20×30×1 25×25×1

4-inch / media cabinet sizes

20×25×4 16×25×4 16×20×4 20×20×4 14×25×4 20×25×5

Don’t see your size?

Measure the printed label first. Odd sizes (e.g. 20×22×1, 17.5×27.5×5) get their own pages later. Until then, order the exact printed size from a specialty seller that lists actual dimensions.