Calculators / Fences and decks
Deck board calculator: how many boards?
Measure the deck and pick your boards. You'll get the board count, the screws, and a straight no if your joists are too far apart for them.
Updated · How we check our numbers
Buy this much
26 boards, 16 ft long
That's 26 rows of 1 board for a 16 ft by 12 ft deck, 416 linear feet in all.
- Deck
- 192 sq ft
- Rows
- 265½ in board + ¼ in gap
- Boards
- 2616 ft
- Screws
- 67613 joists
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Estimate for planning only, not professional advice. Check the manufacturer’s instructions, your local code and a licensed professional before you buy, build or install. Use at your own risk. Terms.
rows = 12 ft × 12 ÷ (5.5 + 0.1875) in = 26, rounded up
boards per row = 16 ft ÷ 16 ft = 1, rounded up
boards = 26 × 1 = 26
joists = 16 ft × 12 ÷ 16 in + 1 = 13
screws = 26 rows × 13 joists × 2 = 676
A 5/4 board that only sits on 2 joists has to be on 12 in centers. Keep every board across 3 joists or more.
Every board end has to land on a joist. Stagger the joints row to row so they don't line up.
Two screws per board at every joist. Boxes list a count, so buy by the number here.
How we work it out
We count rows across the deck, then boards per row. Offcuts don't get reused in the count, so it runs a little over.
rows = deck width in inches ÷ (board width + gap), rounded up
boards per row = deck length ÷ board length, rounded up
screws = rows × joists × 2
The code caps how far a deck board can span. 5/4 wood boards need joists 16 in on center or closer, and 12 in if you lay them at 45 degrees. 2x boards go to 24 in either way. Composite follows the maker. Trex wants 16 in for its standard boards and 12 in on the diagonal.
Where the numbers come from
Guides
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The rest of the deck
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