How we worked it out
Updated as you change the numbers.
- Rows = width ÷ (board + gap) = 144 in ÷ (5.5 + 0.125) in = 25.6, rounded up to 26.
- Linear feet = 26 rows × 16 ft = 416 ft.
- Boards = 416 × 1.1 ÷ 16 ft = 28.6, rounded up to 29.
- Joists = 192 in ÷ 16 in, rounded up, + 1 = 13.
- Screws = 26 rows × 13 joists × 2 = 676.
Method and assumptions
Boards run along the deck length, across the joists. The number of rows is the deck width divided by one board plus its gap. The total linear feet is rows × length; adding the extra and dividing by the board length gives the boards to buy.
Face-screwed boards take two screws at every joist. Hidden fastener systems use one clip per joist crossing instead; the joist and row counts give you that number too (rows × joists).
Tips
- Composite decking often needs closer joist spacing than wood, especially on diagonals (commonly 12 in). Check the manufacturer’s span table.
- Buy boards long enough to span the deck in one piece when you can: fewer joints look better and waste less.
- Screws are sold by the pound or in boxes of a set count; check the count on the box.
Questions
How many deck boards do I need for a 12 × 16 deck?
With 5.5 in boards and a 1/8 in gap, a 12 ft wide deck needs 26 rows. Running 16 ft long, that is 416 linear feet: 29 boards of 16 ft with 10% extra.
Sources
Method and figures checked on . Every worked answer on this page is covered by an automated test. Found a mistake? Tell us.