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Roll Length Formula

I need help to setup a calculator to measure the length of material left on a roll.

The goal is to enter 2 dimensions and have formulas spit out 3 results depending on the materials thickness. Outer diameter in A5, Inner diameter in B5 will give results based on the material thickness.


Thanks to anyone who can help me with my problem.


  • Edge Roll Calculator1.xlsx
    17.7 KB · Views: 1
try in cell B8: =PI()*($A$5^2-$B$5^2)/4/$A8/1000 and copy down.
Thank you, that worked perfectly.

Would you mind explaining to me what the Open then closed bracket after PI achieves? Also, what is the significance of the '$' signs?

Tried all manner of configuration, but didn't think to add either of those.
The parentheses after PI is just what Excel expects! It returns 3.14159.......
The $ symbols are all about absolute v. relative cell references, see: