About this calculator
Count deck boards by rows and stock length, the way you would lay them, plus face screws or hidden clips at every joist.
How it’s calculated
Rows = (deck width + gap) ÷ (board width + gap), rounded up. Boards per row = deck length ÷ stock length, rounded up. Screws = rows × joists × 2.
Worked example
With these inputs:
- Deck length (board direction)
- 16 ft
- Deck width (across boards)
- 12 ft
- Board width (actual)
- 5.5 in
- Gap between boards
- 0.1875 in
- Board length
- 16 ft
- Joist spacing
- 16 in
- Fixing
- Face screws (2 per joist)
- Waste allowance
- 10%
the result is:
- Deck boards
- 29 × 16 ft
- Deck area
- 192 sq ft
- Linear board
- 416 lin ft
- Screws
- 676
Tips from the trade
- Choose a board length that divides the deck neatly, or plan the butt joints over doubled joists.
- Picture-frame borders need extra boards: add them as a second calculation.
- Composite decking often requires 12" joist spacing for diagonal layouts.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and local building codes before ordering.