How Many Boards for a 4x4 Deck?
Deck boards to buy
5 8 ft boards
16 square feet, 5/4 by 6 decking at a quarter inch gap, 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 length4 ft
- Deck width4 ft
- Board face width5.5 in
- Gap between boards0.25 in
- Board length you buy8 ft
- Joist spacing on center16 in
Deck boards to buy5 8 ft boards
| Deck area | 16 sq ft |
|---|---|
| Board rows across the width | 9 |
| Linear feet of decking | 36 lf |
| Boards at 8 ft | 5 |
| Joists at 16 in on center | 4 |
The material list this produces
| Deck boards, 8 ft | 5 |
|---|---|
| Joists, 4 ft | 4 |
| Joist hangers, each | 8 |
| Deck screws, lb | 1 |
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 | 5 8 ft boards |
| 12 ft boards | 3 12 ft boards |
| 16 ft boards | 3 16 ft boards |
| 20 ft boards | 2 20 ft boards |
What else matters here
Nine rows of decking, 36 linear feet, five boards at 8 feet with each one cut in half. There is no version of this where buying 4 foot boards makes sense, because 4 foot decking is not a stocked length and would cost more per foot than the 8 that you cut.
What matters far more than the material on a 4 by 4 is whether it is a deck or a landing. If the walking surface is more than 30 inches above the ground it needs a guard, and if it serves an exterior door it has to be at least as deep as the door swing plus a bit, which for an outswing door is usually more than 36 inches.
The stairs off it are the other half of the job and are frequently the larger half. A landing four feet off the ground needs a stringer, a graspable handrail and a bottom landing of its own, and that assembly costs more than the platform it hangs off.
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 4x4 deck?
Five boards of 5/4 by 6 at 8 feet, each cut in half, giving the 9 rows the width needs.
Does a 4x4 landing need a railing?
If the walking surface is more than 30 inches above grade, yes, and the height and baluster spacing are set by code rather than by preference.
How deep does a landing at a door need to be?
At least the width of the door, and deep enough that the door can swing without pushing you off it. For an outswing door that usually means more than 36 inches.
The deck calculator takes any dimensions you like and hands back the same list.