Thread Length Binding Calculator

Coptic binding's formula factors in the number of sewing stations (roughly 30mm of linking-loop thread per station per signature, on top of twice the book height), because each signature is individually chain-stitched to the one before it at every station. Long stitch has no linking loops at all — thread simply travels up and back along the spine once per signature — so it uses far less thread per signature even at the same book height.

No — only Coptic binding and Japanese stab binding factor station count into their formulas; kettle stitch and long stitch estimates depend only on book height and signature count, not on how many stations you enter. If you're using kettle stitch or long stitch, changing the stations input won't move the thread total.

The 20cm tail allowance covers the actual thread consumed tying off knots at the start and end of sewing, which is a real, fixed material cost regardless of binding style. The 15% safety margin is separate — it's a buffer against tension take-up (thread pulling tighter than expected) and sewing mistakes, applied as a percentage of the whole total rather than a flat amount, since those risks scale with how much thread you're handling overall.

It's an average — total thread length divided by the number of signatures — not a precise per-signature formula, since the safety margin and tail allowance are spread across the whole book rather than added to each signature individually. Use it as a rough guide for cutting individual lengths, but measure your first sewn signature against it before committing the rest of your book to the same length.