Length of Roll Calculator

Use this free length of roll calculator to calculate how much material is on a roll from its diameters and thickness.

How the length of roll calculator works

Length = π × (outer diameter² − core diameter²) ÷ (4 × thickness). Use the same unit for all three.

Frequently asked questions

Does it work for paper, film and tape?

Yes, for any tightly wound material of constant thickness.

Results are estimates for general information only. They are not a substitute for professional advice where applicable. Found a mistake? Report an error.