Enter the load in pounds per square foot and the span in feet into the calculator to determine the allowable area in square feet. This calculator helps in assessing the maximum area that can support the given load.

Allowable Area Formula

The following formula is used to calculate the allowable area.

AA = S / L


  • AA is the allowable area (square feet)
  • L is the load (pounds per square foot)
  • S is the span (feet)

To calculate the allowable area, divide the span by the load.

What is Allowable Area?

Allowable area is a term used in engineering and construction to describe the maximum area that can safely support a given load without exceeding the material’s stress limits or causing structural failure. This concept is crucial for ensuring the safety and integrity of buildings, bridges, and other structures.

How to Calculate Allowable Area?

The following steps outline how to calculate the Allowable Area.

  1. First, determine the load (L) in pounds per square foot.
  2. Next, determine the span (S) in feet.
  3. Next, gather the formula from above = AA = S / L.
  4. Finally, calculate the Allowable Area (AA) in square feet.
  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.

Load (L) = 50 pounds per square foot

Span (S) = 200 feet