Calculating the Number of Deck Boards Needed per Square Footage
Example #1
1. A square foot is 12" wide by 12" in length. Determine square inches in a square foot by multiplying the width and
the length12 x 12 = 144 square inches
2. The standard width of a deck board is 5.5". Multiply this width (5.5”) to its length (consistent with the square
footage area of 12”) to get 66. 66 is how many square inches are in a standard deck board.
3. Dividing 144 square inches by 66 square inches is 2.1818. So 2.182 is how many standard deck boards (5.5” x
12") it takes to cover a square foot. We call this the square footage multiplier.
Example #2 (similar)
1. A square foot is 12" wide by 12" in length. Determine square inches in a square foot by multiplying the width
and the length- 12 x 12 = 144 square inches
2. The standard width of a decking board is 5.5”. Divide the length (12”) by the width (5.5”). You get 2.1818.
2.182 is how many standard deck boards (5.5” x 12") it takes to cover a square foot. We call this the square
footage multiplier.
Calculating the Cost of a Deck Board per Square Footage
Example
1. Cost per linear foot: Let’s say a board is 16' in length and costs $22.08 (without tax). Divide the cost $22.08 by
16’ and you have the linear foot cost of the board$22.08 divided by 16’ = $1.38/ linear foot.
2. Tax: Take $1.38 x .07 (state tax rate) =.0966. Round up to 10 cents per foot tax.
3. Cost plus tax per linear foot: $1.38 + $0.10 = $1.48 / linear foot
4. Cost per sq. ft.: Take the $1.48 per linear foot cost and multiply by the 2.18 you calculated above (square
footage multiplier). This gives a square footage cost for this example of $3.23.
Note: If you are installing Kiln Dried wood, you would also add in the 1/8” or 3/16” gap size to the board width.
So for a 1/8” gap, divide 1 by 8 to get .0125. If the board is 5.5 in width, add 0.125 to get 5.625. This would be
the new # you would use for the board width. Replace the 5.5 figure in the first example above with 5.625. Then
recalculate all. It gets easier each time you do the exercise!