How Many Boards for a 10x10 Deck?
Deck boards to buy
11 20 ft boards
100 square feet, 21 rows of decking, joists 16 inches on center.
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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 length10 ft
- Deck width10 ft
- Board face width5.5 in
- Gap between boards0.25 in
- Board length you buy20 ft
- Joist spacing on center16 in
Deck boards to buy11 20 ft boards
| Deck area | 100 sq ft |
|---|---|
| Board rows across the width | 21 |
| Linear feet of decking | 210 lf |
| Boards at 20 ft | 11 |
| Joists at 16 in on center | 9 |
The material list this produces
| Deck boards, 20 ft | 11 |
|---|---|
| Joists, 10 ft | 9 |
| Joist hangers, each | 18 |
| Deck screws, lb | 3 |
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 | 27 8 ft boards |
| 12 ft boards | 18 12 ft boards |
| 16 ft boards | 14 16 ft boards |
| 20 ft boards | 11 20 ft boards |
What else matters here
Twenty one rows at 10 feet is 210 linear feet, which is eleven 20 foot boards cut in half. In 10 foot stock it is 21 boards, one per row.
Ten feet is the span where the joist size stops being a default. A 2x8 in southern yellow pine at 16 inch centers is good for roughly 13 feet as a joist and a 2x6 for about 9, so a 10 foot span is past what a 2x6 will do and comfortably inside what a 2x8 will.
Those numbers move with the species, the grade, the spacing and the code edition, and a deck that carries a hot tub, a planter or a roof is a different calculation again. The span table in the residential code, or the one the lumber yard hands out, is the one that settles it, not a rule of thumb.
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 10x10 deck?
Eleven boards of 5/4 by 6 at 20 feet cut in half, or twenty one at 10 feet.
What size joists for a 10 foot deck span?
A 2x8 at 16 inches on center handles 10 feet in most species and grades. A 2x6 does not. Check the span table for your species and code edition.
How many joists for a 10x10 deck?
Nine at 16 inches on center, each one 10 feet long, plus the rim joists.
The deck calculator takes any dimensions you like and hands back the same list.