How Many Boards for a 6x6 Deck?
Deck boards to buy
7 12 ft boards
36 square feet, 13 rows of decking, joists 16 inches on center.
When the figures look right, the deck material list downloads as a real PDF with your business details on it, built inside your own browser. Nothing you type is uploaded anywhere.
How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Deck length6 ft
- Deck width6 ft
- Board face width5.5 in
- Gap between boards0.25 in
- Board length you buy12 ft
- Joist spacing on center16 in
Deck boards to buy7 12 ft boards
| Deck area | 36 sq ft |
|---|---|
| Board rows across the width | 13 |
| Linear feet of decking | 78 lf |
| Boards at 12 ft | 7 |
| Joists at 16 in on center | 6 |
The material list this produces
| Deck boards, 12 ft | 7 |
|---|---|
| Joists, 6 ft | 6 |
| Joist hangers, each | 12 |
| Deck screws, lb | 2 |
Board length compared
Same deck, four board lengths. Longer boards mean fewer end joints and more offcut risk.
| Board length | Deck boards to buy |
|---|---|
| 8 ft boards | 10 8 ft boards |
| 12 ft boards | 7 12 ft boards |
| 16 ft boards | 5 16 ft boards |
| 20 ft boards | 4 20 ft boards |
What else matters here
Thirteen rows at 6 feet, 78 linear feet, seven 12 foot boards halved with one half spare. Simple platform, simple order.
A 6 by 6 is very often built to carry a hot tub, and a hot tub is not a decking question. A filled and occupied tub of that footprint runs four to six thousand pounds, which is well over a hundred pounds per square foot, against the forty pounds per square foot a residential deck is designed for.
That load needs its own structure: posts and footings placed under the tub rather than at the deck corners, doubled or tripled beams, and usually joists at 12 inch centers. It is normally cheaper and always safer to set the tub on a concrete pad at grade and build the deck around it flush.
What this calculator assumes
- A nominal 2x6 board is 5.5 inches of actual face. Nominal sizes are not real sizes, which is where most deck orders go wrong.
- Joist count is the span across the deck width at the spacing given, plus one for the last joist.
- Waste is not added. Add 5 to 10 percent if the deck is not a plain rectangle.
Questions people ask
How many boards for a 6x6 deck?
Seven boards of 5/4 by 6 at 12 feet, cut in half, giving the 13 rows the width needs.
Can a 6x6 deck hold a hot tub?
Not as a normal deck. A filled tub is well over a hundred pounds per square foot against a design load of forty, so it needs its own footings, beams and usually 12 inch joist spacing.
Is a concrete pad better than a deck for a hot tub?
Usually yes. A pad at grade carries the load without any of the framing work, and the deck can be built flush around it.
The deck calculator takes any dimensions you like and hands back the same list.