How Many Boards for a 16x20 Deck?
Deck boards to buy
43 16 ft boards
320 square feet, 680 linear feet of decking, joists 16 inches on center.
It does not stop at a number.
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 length20 ft
- Deck width16 ft
- Board face width5.5 in
- Gap between boards0.25 in
- Board length you buy16 ft
- Joist spacing on center16 in
Deck boards to buy43 16 ft boards
| Deck area | 320 sq ft |
|---|---|
| Board rows across the width | 34 |
| Linear feet of decking | 680 lf |
| Boards at 16 ft | 43 |
| Joists at 16 in on center | 16 |
The material list this produces
| Deck boards, 16 ft | 43 |
|---|---|
| Joists, 16 ft | 16 |
| Joist hangers, each | 32 |
| Deck screws, lb | 10 |
Board length compared
Same deck, four board lengths.
| Board length | Deck boards to buy |
|---|---|
| 8 ft boards | 85 8 ft boards |
| 12 ft boards | 57 12 ft boards |
| 16 ft boards | 43 16 ft boards |
| 20 ft boards | 34 20 ft boards |
What else matters here
Sixteen joists at 16 inch centers span the 16 foot direction.
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 deck boards for a 16x20 deck?
About 43 boards of 5/4 by 6 at 16 feet, covering 680 linear feet across 34 rows.
Different numbers?
The deck calculator takes any dimensions you like and hands back the same list.
Other common sizes
4x4 deck5 8 ft boards4x6 deck5 12 ft boards5x5 deck7 8 ft boards4x8 deck9 8 ft boards6x6 deck7 12 ft boards6x8 deck13 8 ft boards6x10 deck11 12 ft boards8x8 deck9 16 ft boards8x10 deck9 20 ft boards8x12 deck17 12 ft boards10x10 deck11 20 ft boards10x12 deck21 12 ft boards12x12 deck20 16 ft boards12x16 deck26 16 ft boards10x20 deck21 20 ft boards12x20 deck33 16 ft boards16x16 deck34 16 ft boards12x24 deck52 12 ft boards16x24 deck51 16 ft boards20x20 deck42 20 ft boards20x30 deck63 20 ft boards