Pick your furnace series. Each page shows the filter sizes from the manufacturer's installation manual or spec sheet, with a link to the document.

Bryant 915SB
Filter sizes auto-extracted from the manufacturer document.
Carrier 59MN7B
Modulating condensing 4-way multipoise gas furnace
Carrier 59SC6A
Multipoise condensing gas furnace
Carrier 59TP6C
Two-stage condensing gas furnace (no internal filter rack)
Carrier 59TP7A
Condensing gas furnace
Daikin DR97MC
97% AFUE upflow/horizontal modulating furnace
Goodman GM9S80-U
80% AFUE single-stage, multi-speed ECM
Goodman GR9S80
80% AFUE single-stage upflow/horizontal furnace (R-32 era)
Lennox SL297NV
Variable-capacity gas furnace; no filter or rack included
Rheem R96V
Two-stage variable-speed multi-position furnace
Trane S9V2
2-stage condensing variable-speed furnace
York / Johnson Controls TM9E
Single-stage ECM multi-position furnace