How do I calculate spine width for a perfect-bound notebook?

Spine width is driven by how many interior pages you have and how thick each sheet is. Get it wrong and your cover art will wrap onto the front or back.

• Formula: spine width = (interior page count / 2) times the paper thickness in inches, since each sheet holds two pages.
• Use the exact caliper of your chosen stock, not a rounded guess.
• Most printers publish a spine calculator, so use it to double-check your math.
• Always confirm the final spine measurement with the printer before locking your cover template.