Enter the effective depth (mm), the diameter of the bar (mm), and the clear cover size (mm) into the Beam Length Calculator. The calculator will evaluate the Beam Length. 

Beam Length Formula

The following formula is used to calculate the Beam Length. 

BEL = ED + D/2 + CS

  • Where BEL is the Beam Length (in)
  • ED is the effective depth (mm) 
  • D is the diameter of the bar (mm) 
  • CS is the clear cover size (mm) 

How to Calculate Beam Length?

The following two example problems outline the steps and information needed to calculate the Beam Length.

Example Problem #1

  1. First, determine the effective depth (mm).
    • The effective depth (mm) is calculated to be : 3.
  2. Next, determine the diameter of the bar (mm). 
    • The diameter of the bar (mm) is measured to be: 4.
  3. Next, determine the clear cover size (mm). 
    • The clear cover size (mm) is found to be: 6.
  4. Finally, calculate the Beam Length using the formula above: 

BEL = ED + D/2 + CS

The values provided above are inserted into the equation below and computed.

BEL = 3 + 4/2 + 6 = 11 (in)


Example Problem #2

The variables required for this problem are provided below:

effective depth (mm) = 6

diameter of the bar (mm) = 8

clear cover size (mm) = 9

Test your knowledge using the equation and check your answer with the calculator.

BEL = ED + D/2 + CS = (in)