Which Home Furnace Filter is the Best? Let’s Ask SCIENCE!

On the amazing Project Farm, Todd wonders what the real performance characteristics and differences are between cheap furnace filters and expensive ones. As always, he creates testing rigs and puts a whole pile of filters, from $1 to $50, to the test.

Tl;Dr: So which one won? It’s complicated. The thicker filters (2″ and 4″) performed better than the common 1″ filter size, but your furnace may not accommodate a larger size. The permanent, washable filter did not perform well. Nor did the cheap ones. Looks like you want to get the thickest filter your furnace will accommodate and one with the most pleats in the outer filter. Overall, the 3M brand filters did really well, like the 600, 1085, and the 1900.