Hi REESE, If the WF-7840's Auto Detect setting is enabled, the printer automatically detects the following sizes: Letter (8.5 × 11 inches [216 × 279 mm]) and A4 (8.3 × 11.7 inches [210 × 297 mm]) in the paper cassette and up to A3+ (13 × 19 inches [329 × 483 mm]) (vertically) and A3 (11.7 × 16.5 inches [297 × 420 mm]), A4 (8.3 × 11.7 inches [210 × 297 mm]), A5 (5.8 × 8.2 inches [148 × 210 mm]), B4 (13.9 × 9.84 inches [353 × 250 mm]) and B5 (7.2 × 10.1 inches [182 × 257 mm]) (horizontally). Regards, Mark - The Epson Team.