Free Online Tool

Deck Calculator — Estimate Materials Instantly

Calculate deck boards, joists, fasteners, and cost for your deck project. Includes diagonal board and material type options.

4
Deck Materials
2
Board Widths
3
Joist Spacing
100%
Free to Use

Enter Deck Details

Board Width

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Enter your deck dimensions and click Calculate to see material estimates.

Frequently Asked Questions

To calculate deck boards, divide the deck width by the board width plus spacing. Multiply by the deck length for linear feet. Add 10% waste or 15% for diagonal layouts.
Standard spacing is 1/8 inch (0.125 in) between boards for proper drainage. Composite decking may require 3/16 inch spacing. Check manufacturer specifications for your material.
Joist spacing depends on decking material and board thickness. Standard spacing is 16 inches on center. Use 12 inches for heavy loads or diagonal patterns, and 24 inches for composite with proper span ratings.
Pressure-treated pine is most affordable. Cedar offers natural beauty. Composite and PVC are low-maintenance but cost more. Choose based on your budget, climate, and maintenance preferences.
Use 2 screws per joist per board. For a standard 16-inch joist spacing, each 12-foot board will need approximately 18 screws. Hidden fastener systems use fewer visible fasteners.
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