Decking Calculator
Calculate the number of deck boards needed.
How It Works
Coverage per board = ((Board width + Gap) ÷ 12) × Board length. Boards = ceil(Area ÷ Coverage).
Example
120 sq ft with 5.5 in boards, 12 ft long, 1/4 in gap: coverage = 5.75 sq ft → 21 boards.
Frequently Asked Questions
What gap should boards have?
1/8–1/4 in for wet-in-service wood to allow drainage and expansion.
Do composite boards need gaps?
Follow the manufacturer — many composites have hidden fasteners that set the gap automatically.
Should I add waste?
Yes, 5–10% for cuts at edges, stairs, and obstacles.