Enter your deck size and board width to get the number of deck boards, linear footage, and screws, plus joist count at your chosen spacing. Add waste for diagonal or picture-frame patterns.
You need approximately
159 boards
covers 158.4 ft² (incl. waste)
Area to cover
158.4 ft²
Exact amount
158.4 boards
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Field notes
Order boards at the deck's full length when you can — a 16 ft board across a 16 ft deck means no butt joints to seal and stagger. Composite usually needs joists at 12 inches on center, not the 16 you'd use for wood, so check the manufacturer before you frame. The 10% waste covers cut-offs and the occasional cupped board; picture-frame borders and diagonals push it higher.
How the decking calculator works
The math behind the tool:
boards = deck width ÷ (board width + gap)
linear ft = boards × deck length × (1 + waste%)
Divide the deck width by the board width plus the gap (typically 5.5 in + 0.25 in) to get boards per row, then multiply by rows and add 10% waste. A 12×16 ft deck needs roughly 33 boards of 16 ft.
How far apart should deck joists be?
Deck joists are usually spaced 16 inches on center; composite decking often requires 12-inch spacing — check the manufacturer and DCA 6 span tables.