Deck board calculator
Enter your deck size, board size, and spacing between boards. Results include area, board count with waste, linear feet of decking, and an estimated screw count.
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Frequently asked questions
- How do I measure deck length and width?
- Measure the outside edges of the deck frame in feet, like laying a rug on the floor. For L-shaped decks, split the layout into rectangles, run the calculator for each, and add the board counts together.
- Why does the gap between boards matter?
- Each row uses the board face width plus the gap. A wider gap means fewer rows across the deck width. Gaps also let water drain and give boards room to expand when wet.
- How much decking waste should I plan for?
- This calculator adds 10% to the board count for cuts, bad ends, and layout waste. Stairs, picture-frame borders, and diagonal patterns usually need extra boards beyond that allowance.
- How are deck screws estimated?
- The tool assumes two screws where each board crosses a joist, with joists spaced 16 inches on center along the deck length. Your actual count may rise if you use hidden fasteners or extra blocking.
- Which way should decking boards run?
- Boards are assumed to run along the deck length, with rows stacked across the width. If you plan the opposite layout, swap your length and width inputs so the rows still match how you will build.
How to use this deck calculator
Measure your deck as a rectangle on the ground. Deck length and width can be entered in decimal feet or feet plus inches. Board width, length, and gap between boards control how many rows fit across the width.
Results include total area, board count with ten percent waste, linear feet of decking, and screw estimates for joists sixteen inches on center. Add extra for stairs and borders before you order.
Related guide
Measure your deck frame, pick board sizes, and order decking and screws without a second trip to the lumber yard.
Read: How Much Decking Do I Need? A Step-by-Step Guide →