What are the most common furnace filter sizes? For residential furnaces, you’ll find three: 16- by 25- by 1-in.; 20- by 25- by 1-in.; and 16- by 20- by 1-in. All About Furnace Filters ...

The filter on the left is clean and new. If your air system is working properly, then your filter will look like the dirty, used one on the right. Douglas Sacha / Getty Images ...

PITTSBURGH, Jan. 21, 2025 /PRNewswire/ -- "I wanted to create a new furnace filter that can be easily and safely gripped and pulled for removal," said an inventor, from Arlington, Tenn., "so I ...