Decking Calculator: Estimate Deck Boards, Joists & Material Costs

Calculate Your Decking Materials & Costs

Use our free Decking Calculator to quickly estimate the number of deck boards, joists, and total material costs for your next outdoor project. Simply input your deck dimensions, board details, and joist spacing to get an accurate material list. Perfect for DIY enthusiasts and professional builders planning their deck construction!

Formula:

The Decking Calculator helps you estimate the quantity of deck boards and joists needed for your project, along with an approximate material cost.

Key Formulas Used:

  • Deck Surface Area (sq ft): L × W
  • Number of Deck Boards: CEIL(((W × 12) / (BW + BS)) × (L / BL) × (1 + WF/100))
  • Number of Joists: CEIL((L × 12 / JS) + 1)
  • Total Material Cost: (NumBoards × CostBoard) + (NumJoists × CostJoist)
Where:
  • L = Deck Length (feet)
  • W = Deck Width (feet)
  • BL = Deck Board Length (feet)
  • BW = Deck Board Width (inches)
  • BS = Deck Board Spacing (inches)
  • JS = Joist Spacing (inches)
  • WF = Waste Factor (%)
  • NumBoards = Estimated Number of Deck Boards
  • CostBoard = Cost per Deck Board
  • NumJoists = Estimated Number of Joists
  • CostJoist = Cost per Joist

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