How this site works
Type a furnace model number, get the filter size its maker prints.
Every size comes from the furnace maker's installation manual or spec sheet, and a second maker document has to agree before a model is published.
Where sizes come from
Each model page names both documents, the page number and the date they were read, with a link to the file. Models whose two documents disagree are held back rather than guessed.
What to double-check
The label on your furnace and the size printed on the edge of the old filter. A filter grille in a wall or ceiling sets its own size, whatever the furnace manual says.
Money
No store or furnace maker pays this site. The filter buttons are plain links to a store page for that size.
Contact
A wrong size, a missing model or a broken document link: [email protected].