How many deck boards do I need for a 12x16 deck?

By the YardBrick Editorial Team · Last updated October 5, 2026

Check it with your own numbers

Open the Deck Calculator with these values

The count

Boards run the 16 ft length. To cover 12 ft (144 inches) of width with 5.5-inch boards and 1/8-inch gaps, you need 144 ÷ 5.625 = 25.6, so 26 rows. Since a 16 ft board covers each row in one piece, that is 26 boards, 416 linear feet in total.

Framing and fasteners

At 16 inches on center across 16 ft, you need 13 joists, each 12 ft long. Two screws per board at every joist works out to about 676 deck screws. Buy a 1,000-count bucket; you will drop some.

Why 16 ft boards fit this deck so well

Matching board length to the deck means no butt joints at all. Butt joints are where water sits, ends check and boards start to look uneven. If your lumber yard only has 12 ft boards, you will need two per row with joints staggered, and blocking under each joint.

Running boards the other way

If the boards run the 12 ft direction instead, you need 35 rows of 12 ft boards, which is more pieces but each is lighter. Swap length and width in the calculator to compare. Joists would then run the 16 ft way, which needs 2x10s on most spans.

Composite decking

• Most composite boards are 5.5 inches wide, the same as wood, so the count holds.
• Gap rules differ: many brands want 3/16 inch side gaps and wider gaps at the ends in hot weather.
• Check the joist spacing on the label. Some composite needs 12 inches on center, which would push the joist count up.

Picture-frame border

A border board around the edge looks sharp and hides cut ends. It adds about 56 linear feet, four more 16 ft boards, and needs blocking around the perimeter.

Permit

A deck over 30 inches off the ground or attached to the house almost always needs a permit and a ledger flashed properly.

For other sizes, use the full Deck Calculator or browse all answers.