Roll Diameter Calculator
Keep core diameter, thickness and pitch in the same length unit. The calculator estimates web length and outside roll diameter.
Enter your job values
Use the real values from your job. Optional fields can stay blank; zero should only be used when the value genuinely does not apply.
Your result will appear here
4 required values are still missing.
Why roll diameter is an estimate
The geometry equates the cross-sectional area of wound material with web length × material thickness. It is useful for planning, but real label stock compresses and traps air differently depending on liner, adhesive, face stock and winding tension.
For equipment-critical limits: use the converter's specified roll OD/core limit and measured finished rolls rather than treating calculated OD as a guarantee.
What the result is useful for
Use this as an early packaging/equipment fit estimate when a maximum roll diameter matters.
How the calculation works
For a tightly wound web, OD ≈ sqrt(core diameter² + 4 × web length × material thickness ÷ π), with web length = pitch × label count.
What this calculator cannot know
Real OD varies with adhesive/liner compressibility, air entrainment, winding tension, matrix removal and material caliper. Use converter/manufacturer roll specifications for equipment-critical limits.