Calculate relative armor thickness and effective line-of-sight armor from plate thickness and slope angle, plus compound angles and a shell penetration check.

Required: actual plate thickness and the armour angle.

Use this for a plate sloped in two directions, or for a hull turned away from the shot.

+ Advanced: material and penetration check

Related Calculators

Effective Thickness Formula

The following example problem outlines the steps and information needed to calculate the Effective Thickness.

ET = T / cos(a)

Variables:

  • ET is the Effective Thickness (line-of-sight thickness; same length units as T)
  • T is the actual (normal) thickness of the armor plate 
  • a is the armor angle from vertical (degrees) 

To calculate the relative armor thickness, divide the actual (normal) thickness by the cosine of the armor angle from vertical.

How to Calculate Effective Thickness?

The following steps outline how to calculate the Effective Thickness.

  1. First, determine the actual (normal) thickness of the armor plate. 
  2. Next, determine the armor angle from vertical (degrees). 
  3. Next, gather the formula from above = ET = T / cos(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 (normal) thickness (in) = 2.5

armor angle from vertical (degrees) = 30

ET = T / cos(a) = ?