Deck Calculator
Estimate decking boards, optional joists and fasteners for one or more rectangular deck sections.
Planning note
Board layout matters
The calculator lays full-length stock along the board-run direction, rounds each row up to whole boards, then adds the allowance you choose.
Rows = deck width ÷ (board width + gap)
Boards per row = deck length ÷ stock length
Boards per row = deck length ÷ stock length
Joist stock is an estimating aid only. Beams, posts, footings, blocking, ledgers, rim boards and structural hardware are not included.
Can offcuts be reused?
Often, yes. This calculator intentionally rounds conservatively and then applies your allowance. A detailed cut plan may reduce the final quantity.
Does this design the deck structure?
No. Joist spacing and stock quantities are planning estimates, not structural design. Confirm spans, loads, footings, connections and local code requirements.