2-Sided Printing (Windows) or Two-Sided Printing Settings (Mac) is gray or not available for selection. What should I do?
Automatic double-sided printing is only available if you have loaded plain paper or other supported paper in these sizes: Letter (8.5 x 11 inches [216 x 279 mm]) and A4 (8.3 x 11.7 inches [210 x 297 mm]).
Note: Double-sided printing is not supported for printing on glossy, thick, and certain matte papers.Related tasks
Selecting Double-sided Printing Settings - Windows
Selecting Double-sided Printing Settings - OS X
Double-sided Printing Options - Windows
Double-sided Printing Options and Adjustments - OS X