Screw Post Spine Width Calculator

Calculate the required post length for your screw post bookbinding project.

Disclaimer: This calculator offers rough guidance only. Actual spine thickness may vary depending on paper and cover material. Always verify with physical materials. We cannot take responsibility for incorrect measurements. When in doubt, use a caliper to measure the stacked height of your project.

Understanding Spine Width for Screw Post Binding

Screw posts (also called bookbinding screws or Chicago screws) are a clean, practical way to bind stacks of paper, cover boards and inserts. The post length you need is based on the combined thickness of all components: paper, covers, and optionally, a bit of tolerance.

Unlike glued or stitched bindings, screw posts offer some flexibility. You don't need compression for strength — just enough length for the screw to engage securely (usually 2–3 full turns). Adding 1 mm of slack is often a good idea: it makes assembly easier, helps screw heads sit flush, and allows for slight variations in material thickness. That said, it's not essential. If your calculated stack height is close to a standard post size, the binding should hold just fine.

If you're working with mixed paper weights, heavy inserts, or aiming for a polished look, you might also consider using washers or spacers. And when in doubt, measure your final stack with a caliper — it's the most reliable method.