Deck Square Footage Calculator
Calculate deck surface area for decking boards. Includes adjustments for board widths and a 10% waste factor for cuts and edge boards.
Deck Calculator
Decking board math
Most decking boards are 5.5 inches wide (nominal 6 inch) with a 1/4 inch gap. So each linear foot of board covers about 0.48 sq ft of deck. A 200 sq ft deck needs roughly 416 linear feet of boards, divided by your board length.
For a 12 ft long deck using 12 ft boards, the math is easy. For deck dimensions that aren't board-length friendly, you'll have butt joints — and those add 5–10% waste.
Composite vs. wood
Composite decking is sold by the linear foot — calculate exact lengths needed plus 10%. Pressure-treated wood is sold by the board, so you may have to round up to standard 8/10/12/16 ft lengths.
Don't forget framing: joists, beams, and ledger boards aren't in your decking sq ft, but they're a major cost. Get a separate framing estimate.
Pro tips
Use longer boards
Longer boards mean fewer butt joints. Try to size your deck to standard board lengths.
Add 10% for waste
Cuts at corners and miters waste material. Plan for 10% extra.
Don't forget fascia
Fascia and skirt boards are sold separately and often forgotten. Measure perimeter × board height.
Stairs need extra
Treads and risers add up. Calculate stair area separately and add it to your deck total.