Deck Board Calculator

Calculate deck boards and total linear feet for a deck build.

Decking
— linear feet
Includes waste.

Usage Tip

Order boards in lengths that span the deck with the fewest butt joints, and stagger any joints you cannot avoid.

THE MATH
boards across = round up( width × 12 ÷ (board width + gap) )
linear feet = boards across × length × (1 + waste ÷ 100)
Deck boards run across the joists with a small gap for drainage. The number across is the deck width divided by the board-plus-gap spacing, and total decking is that times the run length.
Enter the deck length and width, the board width, the gap between boards, and a waste percentage.
The result is total linear feet of decking to buy.
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The calculators and tools on Formula Factory are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. Formula Factory makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.