How many deck boards for a 12x16 deck?
A 12x16 deck in 5/4x6 takes 26 rows of board, which is 29 sixteen-footers with 10% for waste. Board counts and buying plans for every common deck size.
A 12' × 16' deck takes 26 rows of 5/4 x 6 (5 1/2" wide).
At 16' a row that is 416 linear feet before waste, and 29 boards of 16' once 10% is added.
How that is worked out
- Each row covers the board's width plus the gap: 5 1/2" + 3/16" = 5 11/16".
- The deck is 12' — 144" — across the boards, so 144" ÷ 5 11/16" rounds up to 26 rows.
- The last row has to be ripped to 1 13/16". Rip it off the last two rows instead of one if that leaves an awkward sliver — two nearly-full boards look deliberate and one thin one does not.
Decking in 5/4 x 6 (5 1/2" wide), boards running the long way, 10% waste
| Deck size | Square feet | Rows | Row length | Boards to buy | Last row rip |
|---|---|---|---|---|---|
| 8' × 10' | 80 | 17 | 10' | 19 × 10' | 5" |
| 10' × 12' | 120 | 22 | 12' | 25 × 12' | 9/16" |
| 12' × 12' | 144 | 26 | 12' | 29 × 12' | 1 13/16" |
| 12' × 16' | 192 | 26 | 16' | 29 × 16' | 1 13/16" |
| 14' × 20' | 280 | 30 | 20' | 33 × 20' | 3 1/16" |
| 16' × 20' | 320 | 34 | 20' | 38 × 20' | 4 5/16" |
Worth knowing
- The gap matters. 3/16" is the usual call for kiln-dried or composite boards. Pressure-treated stock installed wet can go down tight, because it shrinks apart as it dries — and if you gap wet boards as well, you end up with gaps you can drop a phone through.
- Boards running the long way means fewer, longer boards and fewer butt joints. Running them the short way uses more rows of shorter stock and is what a diagonal or picture-frame pattern needs anyway.
- Any row longer than the stock you can buy has a butt joint in it. Land those over a joist, double that joist or add blocking so both board ends are carried, and stagger them row to row instead of lining them up.
- This is the decking only. Joists, beams, posts, footings, railing and stairs are all separate, and the framing is where the structural decisions are.
Work out your own numbers
- Deck and fence takeoff
Boards, joists, posts, pickets, screws and bags of concrete, with the gaps between boards properly counted.
- Board cut calculator
How many pieces of one length come out of a board of another, with the kerf charged between cuts and the leftover shown.
Related questions
- How many deck boards do I need for a 12x16 deck?
- 26 rows of 5/4x6 running the 16-foot way, which comes to 29 sixteen-foot boards once 10% is added for cuts and culls. The last row needs ripping down, so plan which edge that lands on — against the house is usually the place for it.
- What gap should I leave between deck boards?
- About 3/16" for kiln-dried and composite boards. For pressure-treated stock that is still wet from the treatment plant, lay it tight: it shrinks as it dries and opens its own gap. Gapping wet boards on top of that gives you a deck full of holes a year later.
- Should deck boards run the long way or the short way?
- The long way, usually — fewer rows, fewer boards, and fewer butt joints, since a 16-foot board covers a 16-foot run in one piece. The short way is what you want if you are running a diagonal pattern, or if the joists have to run the other way for the framing to work.