Home & DIY
Decking board calculator
Estimate whole boards across a rectangular deck.
A clear answer. Here’s how.
Rows = ceiling((deck width + gap) ÷ (board width + gap)). Boards per row = ceiling(deck length ÷ stock length). Adds the supplied allowance and rounds up. Reuse of offcuts, joints, framing, fixings and structural suitability are excluded.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Deck length along boards (m)
- 4
- Deck width across boards (m)
- 3
- Board face width (mm)
- 140
- Stock board length (m)
- 4.8
- Gap between boards (mm)
- 5
- Extra boards (%)
- 10
Example result
- Board rows
- 21
- Stock boards per row
- 1
- Boards before allowance
- 21
- Whole boards including allowance
- 24