Free decking calculator

Deck Calculator

Estimate decking surface rows and linear footage from the deck dimensions, actual board face width, board gap and optional board length.

Calculate decking boards

This estimates decking only. It does not size joists, beams, posts, footings or railings. The whole-board result is a minimum linear-foot estimate; seam layout and unusable offcuts can increase the real count.

What this deck calculator estimates

The tool estimates the decking surface only. It determines how many board rows fit across the deck width, multiplies those rows by the board-run length, then applies any extra percentage you choose.

rows = ceiling(deck width ÷ effective board width)

decking linear feet = rows × deck length

Why framing is excluded

Substructure is a safety-critical design problem, not just a material-count problem. Trex separates deck dimensions, substructure, decking and railing in its own planning workflow and describes the framework as critical to safety. This calculator therefore does not size joists, beams, posts or footings.

See Trex's deck planning calculator.

About the whole-board estimate

If you enter a stock board length, the calculator converts purchase linear footage into a minimum whole-board count. Seam layout, stagger requirements, board defects and unusable offcuts can increase the real quantity, so verify the result against the final board layout before purchasing.

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