How Many Decking Boards Do I Need?

M. John
composite deck floor in a garden with chairs and table

How many decking boards do you need? Before you start building your deck, it’s good to know how many Ultradecking boards you will need for your project. The simplest way to determine how much decking you will need to build your deck is to calculate it yourself or use a decking calculator. However, some factors can determine the number of boards to use. We will consider those factors before we consider the number of boards you will need.

Factors That Determine the Number of Deck Boards

Composite decking floor installed outdoor
Ensuring you get your decking boards calculation right is important

If you want to know how many decking boards you will need, you need to know the square footage of your deck. Apart from that, your deck design is also important. You also need to know the board size you want to use.

Square Footage

However, by determining the dimensions of your deck and its spacing, you should be able to calculate how many decking boards you will need. For you to do so, you need to calculate the square footage of your deck. You can determine the square footage by calculating the length and the width of the deck.

However, the dimensions for the deck boards may differ depending on your deck design. If you want to build a deck with sections, divide it into parts, then find the square footage of each part and add them together. Once you know the square footage of your deck, you can input the number into a decking calculator to know how many decking boards you need for your project.

Deck Design

The way you design your deck can also help you know how many decking boards you will need. If you have a rectangular or square deck, you should get a wooden board to run the length of your deck.

Board Size

Knowing the length of the board will determine how much waste you will have. Both composite and wood have a board length of  8, 10, 12, 14, 16, to 20.’

A wooden board is 5 ½” wide. Likewise, a 5/4” thick wood decking is 1” thick. Composite decking, on the other hand, has widths ranging from 5 ½” to 5 ¼”. The thicknesses of the board also range from 1” to 2”.

How to Calculate the Number of Decking Boards

Step One: Find Square Footage

The first step in determining the amount of wood you will need is to calculate the square footage. To determine the square footage, start by calculating the length and width of your deck. After getting the length and the width, find the square footage by multiplying its length with the width. For instance, a 12×12 deck will have 4 square feet of square footage.

Step Two: Calculate the Board Size

The second step is to determine the size of the wood or board. The common decking size is a 5/4” thick by 6” wide board of any length.

We are also going to use a board size of  5/4”x 6” x12’. When calculating the number of wood or composite decking, you should consider the spaces you will leave between the deckings. The board will have a spacing of ⅛”, so each of the boards, plus one space, will make up a total of 5 ⅝”.

Step Three: Determining the Number of Deckings

Now, to know how many decking boards you will need, you will have to divide 5.625 (⅝) with the square footage(144). The result will be 25.6, approximately the result to make 26. You will need 26 boards that are 12′ long to make a 12 x 12 deck.


To know how many decking boards you will need for your project, you must find the square footage. Then the board size before getting the number of deckings.


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