Work out spine width instantly with clear inputs, formula shown and shareable results.
The text block thickness is pages divided by the paper's pages-per-inch bulk, converted to millimetres, with cover board added on each side. Getting the spine wrong by a millimetre wraps the front cover artwork around the edge, which is why printers publish a pages-per-inch figure for every stock.
Spine width
spine = pages / pages per inch x 25.4 mm + 2 x cover thickness
Cover width
flat cover width = 2 x trim width + spine width
spine = pages / pages per inch x 25.4 mm + 2 x cover thickness. The text block thickness is pages divided by the paper's pages-per-inch bulk, converted to millimetres, with cover board added on each side.
Getting the spine wrong by a millimetre wraps the front cover artwork around the edge, which is why printers publish a pages-per-inch figure for every stock.
Enter page count, paper bulk in pages per inch, cover board thickness each side, trim width for the cover. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.