Deck board calculator

How many deck boards you need for a rectangular deck — with gap, waste, and per-row breakdown.

Calculated in this browser. Nothing is sent anywhere.

Boards run lengthwise: rows = deck width ÷ (face width + gap), pieces per row = deck length ÷ board length. Both round up, then waste % applies. Cuts between boards are not optimized — buy a spare for mistakes.

How to use

  1. Enter deck length and width.
  2. Enter board width and the gap between boards.
  3. Read the board count with waste included.

What it supports

Boards run across the deck's width; count = ⌈length ÷ (board + gap)⌉, then waste % is added and rounded up. Metric or imperial units, arbitrary board lengths are reported as linear metres/feet needed. Diagonal or herringbone layouts are not covered.

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