Enter the finished deck size
Add the deck length and width in feet. The calculator assumes deck boards run along the length and rows are counted across the width.
Free Woodworking Tool
Free Deck Board Calculator
A deck board calculator estimates how many boards you need by dividing the deck width into board rows, splitting long runs by board length, and adding a waste allowance. This free decking calculator also estimates linear feet, material cost, and fasteners so you can plan a deck material list before buying lumber.
Deck dimensions
Boards are assumed to run along the deck length.
Shopping list
Decking estimate
Boards to buy
29
26 before waste
Deck rows
26
1 board per row
Linear feet
464
including waste
Fasteners
754
two per joist crossing
| Deck area | 192 sq ft |
|---|---|
| Board coverage width | 5.63 in |
| Base board count | 26 boards |
| Recommended count | 29 boards |
| Material cost | $536.50 |
| Fastener estimate | 754 screws |
Estimate notes
- Assumes boards run along the 16 ft direction and rows are counted across the 12 ft width.
- Uses 5.5" board width with a 0.125" gap for each row of decking.
- Adds 10% waste for end cuts, layout mistakes, damaged boards, and board selection.
- Fastener estimate assumes two fasteners at each joist crossing with 16" joist spacing.
How to use the deck board calculator
Set board size and spacing
Choose the actual board face width, the gap between boards, and the stock board length you plan to buy.
Add waste, price, and joist spacing
Set a waste factor for cuts and selection, enter the price per board, and choose joist spacing for a fastener estimate.
Review the shopping estimate
Use the board count, linear feet, cost, and fastener estimate as a planning checklist before confirming your final layout.
Deck board calculator FAQ
How do I calculate how many deck boards I need?
Divide the deck width by the board face width plus the spacing gap to get the number of rows. Then divide the deck length by the board length to find boards per row. Multiply those numbers and add waste for cuts and mistakes.
How much waste should I add for deck boards?
A 10% waste factor is a reasonable default for a simple rectangular deck. Use 12% to 15% when boards need many cuts, the layout has picture framing, or you want more room to reject damaged boards.
What gap should I leave between deck boards?
Many deck layouts use about 1/8 inch to 1/4 inch between dry boards, but the right gap depends on the material, moisture content, climate, and manufacturer instructions.
Does this calculator include joists or framing lumber?
No. This calculator estimates deck surface boards and fasteners only. Joists, beams, posts, blocking, flashing, railing, stairs, and hardware need a separate framing estimate.
Should deck boards run the length or width of the deck?
Deck boards usually run perpendicular to the joists. This calculator assumes boards run along the deck length. Swap the length and width inputs if your board direction is different.
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