Enter the length and width of the deck, as well as the total number of deck posts, into the calculator to determine the deck post spacing; this calculator can also evaluate any of the variables given the others are known.

Deck Post Spacing Formula

The following formula is used to calculate the deck post spacing:

DPS = (L - W) / (N + 1)


  • DPS is the deck post spacing
  • L is the length of the deck
  • W is the width of the deck
  • N is the total number of deck posts

To calculate the deck post spacing, subtract the width of the deck from the length of the deck. Divide the result by the total number of deck posts plus 1.

What is a Deck Post Spacing?

Deck post spacing refers to the distance between the posts that support a deck. This is a crucial aspect of deck construction as it directly impacts the stability and safety of the deck. The spacing is determined by several factors including the size and type of the deck, the weight it is expected to bear, the type of wood used, and local building codes. Typically, deck posts are spaced between six to eight feet apart. However, for larger decks or decks designed to hold heavy loads, the posts may need to be closer together. Proper deck post spacing ensures that the deck is structurally sound and can safely support the intended load.

How to Calculate Deck Post Spacing?

The following steps outline how to calculate the Deck Post Spacing.

  1. First, determine the length of the deck (in feet).
  2. Next, decide on the maximum spacing between the deck posts (in inches).
  3. Next, convert the maximum spacing from inches to feet.
  4. Finally, calculate the number of deck posts needed by dividing the length of the deck by the converted maximum spacing.
  5. After calculating the number of deck posts, round up to the nearest whole number to ensure there are enough posts for the entire length of the deck.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Length of the deck (in feet) = 12

Maximum spacing between deck posts (in inches) = 6