Calculate roll length, outside diameter, core diameter, material thickness, or turns from roll dimensions in inches, feet, meters, and more.
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Roll Length Formula
The following formula is used to calculate the length of a roll of material.
L = pi * (OD^2/4 - ID^2/4) / t
- Where L is the roll length
- OD is the outer diameter
- ID is the inner diameter
- t is the thickness
A roll length is calculated by multiplying the difference between the diameters squared over 4, by pi, then dividing by the thickness.
Roll Length Definition
A roll length is defined as the length of a material that has been rolled into a cylindrical form with a given material thickness.
Example Problem
How to calculate roll length?
First, determine the outer diameter. For this problem, we are looking at a roll of duct tape that has an outer diameter of 5 inches.
Next, determine the inner diameter. For this example, the duct tape has an inner diameter of 2 inches.
Next, determine the material thickness. On average, duct tape has a thickness of .011 inches, so that will be used.
Finally, use the formula to calculate the roll length:
L = pi * (OD^2/4 - ID^2/4) / t
= 3.14159 *(5^2/4 - 2^2/4)/.011
= 1499.39 inches.
