What trim sizes are supported?

The Interior Formatter supports the standard trade-book trims:

• 5 × 8 in
• 5.25 × 8 in
• 5.5 × 8.5 in
• 6 × 9 in

These cover the vast majority of novels and nonfiction across all four supported printers — KDP, IngramSpark, Lulu, and B&N Press.

Choose the same trim in the interior and the Cover Maker — they have to match, since the cover wraps the interior. If they differ, your book won't assemble correctly at the printer.

Check the binding before you settle on a trim

Trim size and binding are linked, and not every printer prints every combination. Lulu does not offer 5.25 × 8 at all, and hardcovers are available at fewer trims than paperbacks. If you're planning a hardcover or a dust jacket, check the grid in Which printers and bindings can I make a cover for? before you format the interior — changing trim later re-flows the whole book and changes your page count.