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Wound Material Roll Length

Wound Material Roll Length: explicit inputs, a worked example and clearly stated assumptions.

Runs on your deviceUpdates as you typeFormula & example ↓
01

Your inputs

Adjust the values to explore a different result.

mm
Enter outer roll diameter in mm.
mm
Enter core diameter in mm.
mm
Enter material thickness in mm.

Formula

length=π(D²−d²)/(4 thickness), converted from mm to m.
  • Use the units shown beside each field.
  • Results update automatically whenever you change an input.
  • Displayed values use up to four decimal places, or scientific notation for very small or large numbers. Calculations use standard floating-point arithmetic; exact integer and fraction tools identify their own precision rules.
  • Tightly wound uniform material with no voids or compression. The approximation uses annular cross-sectional area.

Example Calculation

Example inputs
  • Outer roll diameter: 100 mm
  • Core diameter: 40 mm
  • Material thickness: 0.1 mm

100 mm outer diameter around a 40 mm core at 0.1 mm thickness holds about 65.973 m.

Frequently asked questions

How do I use this calculator?

Enter outer roll diameter, core diameter, material thickness. The result updates automatically. Use Reset to restore the example values.

What method does it use?

length=π(D²−d²)/(4 thickness), converted from mm to m.. Tightly wound uniform material with no voids or compression. The approximation uses annular cross-sectional area.

Why might a rounded result differ?

The calculation keeps full numeric precision internally, then rounds the displayed result. Rounding intermediate steps by hand can produce a slightly different answer.

Are my inputs saved online?

No. This calculator processes your inputs in your browser. A recently used list stores only calculator names on this device, not your entered values.

Check the assumptions and units before using this result. Read about calculation methods.