Deck Board Calculator
Plan your deck build with accurate material estimates. Enter your deck dimensions to calculate the number of deck boards, joists, screws, and total linear footage — with an adjustable waste factor for cuts and mistakes.
Enter Your Deck Dimensions
Full Breakdown
Deck Area
Boards (Exact)
Boards (w/ Waste)
Board Size
Linear Feet
Joists
Deck Screws
How to Use This Calculator
- Enter your deck length and width in feet.
- Select the board width (5.5" is standard for most decking).
- Choose the board length available at your supplier.
- Set the gap spacing between boards (⅛" is standard for wood).
- Select a waste factor — 10% is recommended for most builds, 15% for diagonal or complex layouts.
- Click "Calculate Deck Materials" for your full material list.
The Formula
Boards Across = (Deck Width × 12) ÷ (Board Width + Gap)
Boards Along Length = Deck Length ÷ Board Length
Total Boards = Boards Across × Boards Along Length × (1 + Waste%)
Joists are calculated at 16" on center: (Deck Length × 12 ÷ 16) + 1.
Deck screws are estimated at ~350 per 100 sq ft (2 screws per board per joist crossing).