How many boards for a 10 × 12 deck?
A 10x12 deck is 120 sq ft of surface. With standard 5.5-inch boards, a 1/4-inch gap, and 10% waste, that's 18 sixteen-foot boards.
| Board length | Boards needed (incl. 10% waste) |
|---|---|
| 12 ft | 23 |
| 16 ft | 18 |
| 20 ft | 14 |
Estimates are for planning. Confirm quantities against your measured site and product packaging before ordering, and follow local building codes.
Planning the rest of the 10x12 deck
Boards are the visible quarter of a deck project. Under them you'll frame joists at 16 inches on center (12 for composite on a diagonal), and the whole structure needs footings sized to your frost depth. For the full budget picture, see what a deck really costs, and if you're weighing this against a ground-level alternative, the comparison lives on our sister site: deck vs. patio costs. Stairs? The stair stringer calculator turns your deck height into riser and tread counts.
Frequently asked questions
How many deck boards do I need for a 10x12 deck?
Using standard 5.5 inch wide boards with a 1/4 inch gap and 10% waste, a 10x12 deck takes about 18 16-ft boards, 23 12-ft boards, or 14 20-ft boards. Match board length to your deck dimension to minimize butt joints.
How much does decking for a 10x12 deck cost?
Surface boards only: pressure-treated runs about $480 to $960 installed ($4 to $8/sq ft), composite about $1,440 to $3,000 ($12 to $25/sq ft). Framing, footings, railings, and stairs are separate.
What board length should I buy for a 10x12 deck?
Boards that span the full 12 ft dimension avoid butt joints entirely, so 16-ft boards are the clean choice here.