Deck board calculator
Enter the deck size, board width and gap. The calculator counts rows, boards and the screws to fasten them.
Deck boards
29 16 ft boards
- Rows of boards
- 26 rows
- Linear feet
- 416 ft before waste
- Deck screws
- 676 screws (2 per joist)
- Deck area
- 192 sq ft
How it works
Each row of decking takes up one board width plus one gap. The calculator divides the deck width by that to count rows, multiplies rows by the deck length to get linear feet, adds waste, and divides by your board length.
Screws assume two per board at every joist. If you use hidden fasteners, count clips with the manufacturer’s coverage chart instead.
Example
With deck length (direction boards run) 16 ft, deck width (across the boards) 12 ft, board width: 5½ in (5/4×6 or 2×6), gap between boards 0.125 in, board length: 16 ft, joist spacing: 16 in on center, waste 10%, the answer is 29 16 ft boards.
Tips before you buy
- Pick a board length that lets seams land on joists, and stagger seams from row to row.
- Wood decking is often installed tight or with a small gap, because it shrinks as it dries. Composite boards have a required gap; follow the manufacturer.
- Many composite boards need joists at 12 inches on center, especially on diagonal layouts.
- Buy a few extra boards so you can skip ones with ugly knots or a bad crown.
Common questions
How many deck boards for a 12×16 deck?
With 5½ inch boards running the 16-foot direction and a 1/8 inch gap, about 29 boards at 16 feet, including 10% waste.
What gap should deck boards have?
Commonly 1/8 to 1/4 inch for dry lumber and composite. Wet pressure-treated wood is often installed tight because it shrinks.
How many screws do I need per square foot of deck?
With 5½ inch boards over joists at 16 inches, about 3.2 screws per square foot.