Timber & Decking Calculator
Calculate boards, lineal metres, volume, and weight for any timber deck or floor. Supports all board sizes and gap widths.
How to calculate decking timber
Boards run along the length of the deck. The number of boards is determined by how many fit across the deck width, accounting for gaps between boards.
Board width tips
- 90 mm boards give a fine, traditional look and are less prone to cupping than wider boards.
- 140 mm boards are the most popular width in Australia — a good balance of look and stability.
- 190 mm boards lay faster but are more susceptible to movement and cupping if not well-seasoned.
- Gap size: 3–5 mm gaps are typical for hardwood; allow for slight expansion. 8 mm is used for particularly wet climates.
Fun fact: Merbau (kwila) has long been Australia's most popular decking timber, but is being phased out due to deforestation in Southeast Asia. Spotted gum and blackbutt are sustainable and equally beautiful Australian alternatives.
Want a deeper guide?
Read: Building a Deck in Australia: Timber Calculator Guide and Cost Breakdown — how to choose timber, allow for wastage, and budget for the parts people usually forget.
Read the decking guide →