Work out deck board quantity instantly with clear inputs, formula shown and shareable results.
Decking rows are set by the board pitch, the board width plus the drainage gap. Rows equal deck width divided by that pitch, and total linear metres is rows times deck length. Converting to a purchase quantity divides by the stock length and adds a small allowance for end cuts.
Rows
Rows = ceil(deck width / (board width + gap))
Boards
Boards = ceil(rows x deck length / stock length x 1.05)
Rows = ceil(deck width / (board width + gap)). Decking rows are set by the board pitch, the board width plus the drainage gap.
It lets water drain and debris fall through, and it accommodates the seasonal movement of timber. Too tight a gap causes cupping and standing water.
This calculator takes 4 inputs: Deck length, Deck width, Board width, Gap between boards. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.