Deck Board Calculator
Work out how many deck boards you need from your deck size and board dimensions, including the gap between boards and a waste allowance.
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ft
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Deck boards needed
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Estimated quantities for your project — prices and stock vary by store.
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How the deck board calculator works
Rows = ⌈ deck width ÷ (board width + gap) ⌉ · Boards = rows × boards per row + 10%
We figure out how many rows of boards span the deck (accounting for the gap between boards), how many boards it takes to run each row's length, then add 10% for cuts and waste.
Frequently asked questions
How much gap should I leave between deck boards?
1/8 inch is typical for treated lumber that will shrink as it dries; composite boards often use 3/16 inch.
Should I buy extra deck boards?
Yes — order about 10% extra for cuts, mistakes, and future repairs, and try to buy from one batch for consistent color.