Enter the actual width (in) and the angle of the armor (degrees) into the Effective Thickness Calculator. The calculator will evaluate the Effective Thickness. 

Effective Thickness Formula

The following two example problems outline the steps and information needed to calculate the Effective Thickness.

ET = W / sin(a)


  • ET is the Effective Thickness (in)
  • W is the actual width (in) 
  • a is the angle of the armor (degrees) 

To calculate the relative armor thickness, divide the actual width by the sine of the angle of the armor.

How to Calculate Effective Thickness?

The following steps outline how to calculate the Effective Thickness.

  1. First, determine the actual width (in). 
  2. Next, determine the angle of the armor (degrees). 
  3. Next, gather the formula from above = ET = W / sin(a).
  4. Finally, calculate the Effective Thickness.
  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.

actual width (in) = 2.5

angle of the armor (degrees) = 30

ET = W / sin(a) = ?