Deck Calculator
Estimate decking boards, joists, and materials for a deck.
How It Works
Joists = ceil((Length × 12) ÷ Joist spacing) + 1. Boards = ceil((Width × 12) ÷ 6).
Example
A 12 ft × 10 ft deck at 16 in spacing: 10 joists and 20 decking boards.
Frequently Asked Questions
What joist spacing should I use?
12–16 in on center for most residential decks; 24 in only with approved decking products.
Why 6 in for decking?
A typical 2×6 board with a small gap works out to about one board every 6 in of width.
Does this include beams and posts?
No — beams, posts, footings, and hardware are additional to this estimate.