Deck Material Calculator
Calculate the amount of decking boards, joists, fasteners, and other materials needed for your deck project based on dimensions and spacing.
Published by:
isCalculator Editorial Team
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How to use this tool?
This calculator estimates the materials needed for a deck: boards, joists, and fasteners. All measurements are in feet (deck dimensions, board length) or inches (board width, gap, joist spacing).
- Enter Deck Dimensions – Provide the Length and Width of the deck in feet (e.g., 20 ft by 12 ft).
- Specify Board Details – Input the Board Width (in inches, e.g., 5.5), Gap Between Boards (in inches, e.g., 0.125), and Board Length (in feet, e.g., 12).
- Set Joist Spacing – Enter the distance between joists in inches (e.g., 16).
- Click "Calculate" – The results will show:
- Boards needed – Total number of deck boards (rounded up).
- Joists needed – Number of joists (rounded down).
- Fasteners needed – 2 fasteners per joist per board intersection.
- Total square footage – Deck area (Length × Width).
If any input is invalid or missing, an error message will appear. Ensure all values are positive numbers (gap can be zero).
Previous Results
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Frequently Asked Questions
Measure the length and width of the deck area in feet. For board width and gap, use inches. Joist spacing is typically 16 inches on center.
This calculator assumes a rectangular deck. For irregular shapes, divide into rectangles and calculate separately, then sum materials.
No, it does not. We recommend adding 10-15% extra for waste, cuts, and mistakes.