Deck Calculator
Estimate deck boards and screws needed from deck length and width.
Boards needed
24 boards
- Deck area
- 120 sq ft
- Screws (est.)
- 420
How we calculate this
Total linear feet of boards = deck area ÷ board width (in feet). Boards needed = total linear feet (plus waste) ÷ board length. Screws are estimated at roughly 350 per 100 sq ft, a standard contractor rule of thumb.
Example
Common mistakes
- Not accounting for board gaps (typically 1/8 to 1/4 inch), which slightly increases coverage per board.
- Forgetting picture-frame or diagonal layouts add significant waste over a straight run.
- Underestimating fasteners — hidden clip systems and screws have different coverage rates.
Frequently asked questions
How do I calculate how many deck boards I need?
Divide your deck area by the board width (in feet) to get total linear footage needed, then divide by the board length to get a board count. Add a waste allowance for cuts.
How many screws per deck board?
Roughly 2 screws per joist crossing, with joists typically 16 inches on center — about 350 screws per 100 sq ft of decking.
Related calculators
Estimates are provided for planning purposes. Actual material requirements may vary based on supplier specifications, compaction, site conditions, installation method, waste, and local code.