Enter the outer radius (in) and the inner radius (in) into the Annular Ring Calculator. The calculator will evaluate the Annular Ring. 

Annular Ring Formula

The following two example problems outline the steps and information needed to calculate the Annular Ring.

AR = 2*pi*(R+r)


  • AR is the Annular Ring (in)
  • R is the outer radius (in) 
  • r is the inner radius (in) 

How to Calculate Annular Ring?

The following steps outline how to calculate the Annular Ring.

  1. First, determine the outer radius (in). 
  2. Next, determine the inner radius (in). 
  3. Next, gather the formula from above = AR = 2*pi*(R+r).
  4. Finally, calculate the Annular Ring.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

outer radius (in) = 5

inner radius (in) = 3

AR = 2*pi*(R+r) = ?