How it works

1 Deck dimensions

Enter length and width in metres. Results update live as you type.

2 Decking direction

Lengthwise means boards run along the long dimension. Widthwise means boards run across the short dimension. This affects joist and bearer orientation.

3 Board width

88 mm or 140 mm face width. A 3 mm expansion gap is automatically added per board in the calculation.

4 Joist spacing

400, 450, or 600 mm centres. 450 mm is common for residential decks with standard decking boards.

5 Bearer spacing

The distance between bearer rows. Typically 1200–1800 mm depending on joist size and span tables.

6 Lineal metres

Shown separately for boards, joists, and bearers — so you can order each timber size precisely from your supplier.

Aries Builders Ltd · Ōtāhuhu, Auckland · Licensed Building Practitioners