Deck Board Calculator
Decking boards and screws from deck size and board dimensions.
1/8 to 1/4 in. Wet pressure-treated boards shrink, so they are often laid tight.
You need
29 boards
Waste included. Cull twisted boards at the yard; they do not straighten.
- Board rows
- 26 rows
- Deck area
- 192 sq ft
- Deck screws
- 675 screws
Estimates only. Verify quantities before ordering.
How this is calculated
Rows = deck width in inches / (board width + gap), rounded up. Boards per row = deck length / board length, rounded up. Total = rows x boards per row plus waste. Screws assume about 3.5 per square foot (two per board at each 16 in joist).
Enter the deck dimensions, pick your board size and gap, and this calculator counts the boards and screws. It works row by row: how many board widths (plus gaps) span the deck, times how many board lengths cover each row, plus waste for cuts and culls.
Buy boards as long as your deck allows. A 16 ft deck covered with 16 ft boards has no butt joints, which look better and last longer than seams. Where joints are unavoidable, they must land on a joist, stagger between rows, and that cutting is why the waste factor defaults to 10%.
Boards for common deck sizes
Rows assume 5.5 in boards, a 1/4 in gap, 16 ft stock, and 10% waste.
| Deck size | Boards | Screws |
|---|---|---|
| 10 x 10 ft | 24 boards | 350 screws |
| 12 x 12 ft | 29 boards | 500 screws |
| 16 x 12 ft | 29 boards | 675 screws |
| 20 x 14 ft | 66 boards | 975 screws |
| 24 x 16 ft | 75 boards | 1,350 screws |
Common questions
How many deck boards do I need per square foot?
With standard 5.5 inch boards and a 1/4 inch gap, each linear foot of board covers about 0.48 square feet, so plan on roughly 2.1 linear feet of decking per square foot of deck, plus waste. A 200 square foot deck is about 420 linear feet of boards.
What gap should I leave between deck boards?
Aim for 1/8 to 1/4 inch in service. Kiln-dried and composite boards are installed at that gap. Wet pressure-treated lumber is usually laid tight because it shrinks about 1/4 inch as it dries, opening its own gap. Check the moisture of your boards before choosing.
Screws or hidden fasteners?
Face screws are cheapest, strongest, and easy to service: use coated or stainless deck screws, two per board at every joist. Hidden clip systems give a cleaner surface on grooved composite boards at extra cost. Never use uncoated screws or nails on treated lumber; the chemicals corrode them.
Which way should deck boards run?
Perpendicular to the joists, always. Beyond that, boards running parallel to the house's long dimension usually look best and shed water along their length. If the deck is longer than your boards in one direction, run boards the other way to avoid butt joints entirely.