How to Calculate Deck Calculator
What is Deck Calculator?
A deck calculator estimates the decking boards, joists, posts, and fixings needed to build a timber or composite deck. It also estimates the total cost based on material choice.
Step-by-Step Guide
- 1Calculate deck area (length × width)
- 2Board count: area ÷ (board width − gap) × board length; add 10% for diagonal or waste
- 3Joist spacing: typically 400mm centres; number = deck length ÷ 0.4 + 1
- 4Posts: typically every 1.5–2m where frame meets ground
Worked Examples
Input
4m × 3m deck · 140mm×28mm boards at 5mm gap
Result
~20 boards at 4m length
3m ÷ 0.145 = 20.7 runs