Enter the total span (ft) and the total depth (ft) into the Calculator. The calculator will evaluate the Span To Depth Ratio. 

Span To Depth Ratio Formula

STD = S / D


  • STD is the Span To Depth Ratio (ft/ft)
  • S is the total span (ft)
  • D is the total depth (ft)

To calculate Span To Depth Ratio, divide the span length by the total depth.

How to Calculate Span To Depth Ratio?

The following steps outline how to calculate the Span To Depth Ratio.

  1. First, determine the total span (ft). 
  2. Next, determine the total depth (ft). 
  3. Next, gather the formula from above = STD = S / D.
  4. Finally, calculate the Span To Depth Ratio.
  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.

total span (ft) = 50

total depth (ft) = 790