Deck Board Calculator
Find how many deck boards to buy. A 16 x 12 ft deck laid with 5.5 inch boards needs about 39 twelve-foot boards with waste.
How many deck boards do you need
Divide the deck width by the board width plus the gap to get the number of rows. Multiply by the deck length for total linear feet, add waste for cuts, and divide by the board length you plan to buy.
A 16 x 12 ft deck with 5.5 inch boards and a 1/4 inch gap has 26 rows and 416 linear feet of decking. With 10% waste that is 39 boards of 12 ft, about $858.00 at $22 each.
Tips
- Standard 5/4 x 6 decking is 5.5 inches wide, 2×6 boards are also 5.5 inches.
- Leave about 1/8 to 1/4 inch gaps for drainage and expansion.
- Pick board lengths that match deck length to reduce cut waste. Stagger butt joints over joists.
- Add 15% waste for diagonal layouts.
Planning the whole structure? Use the deck calculator for joists, footings and total cost.
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Frequently asked questions
How many deck boards do I need for a 12×12 deck?
About 24 rows of 5.5 inch boards, or roughly 288 linear feet before waste.
What gap should I leave between deck boards?
1/8 to 1/4 inch for pressure treated wood that dries and shrinks, and as specified for composite.
How many screws per deck board?
Two screws at every joist the board crosses.
How much waste should I add?
10% for straight layouts, 15% for diagonal or pattern layouts.
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