Enter the total load and the deck area into the calculator to determine the average applied load per unit area (for example, pounds per square foot, psf). This result can be compared to a deck’s designed/allowable loads, but it does not by itself verify structural safety or building-code compliance.

Deck Load (psf) Calculator

Enter any 2 values to calculate the missing variable

Related Calculators

Deck Strength Formula

The following formula is used to calculate the average applied load per unit area on a deck:

DS = L / A

Variables:

  • DS is the average applied load per unit area (e.g., psf)
  • L is the total load on the deck (e.g., pounds-force)
  • A is the deck area (e.g., square feet)

To calculate DS, divide the total load on the deck by the deck area. This gives an average load intensity that can be compared to design loads; it does not by itself determine the deck’s structural capacity.

What is Deck Strength?

In this calculator, “deck strength” refers to the average load per unit area applied to the deck surface (often expressed in pounds per square foot, psf). Actual structural capacity depends on the deck’s design (joist size/span/species/grade, spacing, connections, beams, posts, footings, and local code requirements).

How to Calculate Deck Strength?

The following steps outline how to calculate the Deck Strength:

  1. First, determine the total load on the deck (L) in pounds (or other force units).
  2. Next, determine the area of the deck (A) in square feet (or other area units).
  3. Next, gather the formula from above = DS = L / A.
  4. Finally, calculate DS (the average load per unit area) in pounds per square foot (psf).
  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 on the deck (L) = 5000 pounds

Area of the deck (A) = 100 square feet

Deck load (DS) = 5000 ÷ 100 = 50 pounds per square foot (50 psf)