Decking Calculator
Work out how many deck boards and the total board length you need, plus the cost — from your deck size, board width, and gap. Free, instant, no sign-up.
Deck size
Boards
Your decking estimate
Deck area20,0 m²
Deck boards (rows)28 rows
Board length to buy154,0 m
Estimated board costR 13 090
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Add labour and your margin, then send a professional estimate from your phone — free, no card.
Create a free account →How the decking calculation works
board pitch = (board width + gap) ÷ 1000 board rows = ⌈deck width ÷ board pitch⌉ board length = rows × deck length × (1 + waste%) board cost = board length × price per m
FAQ
- How do I calculate how many deck boards I need?
- Divide the deck width by the board pitch (board width plus the gap) to get the number of board rows, then multiply by the deck length and add waste. This calculator does it and gives the total board length to buy.
- What gap should I leave between deck boards?
- Leave 3–6 mm between boards for drainage and timber movement. Hardwoods that move more take a slightly larger gap; check the board manufacturer’s guidance.
- How much waste should I allow for decking?
- Allow about 10% for cuts, board ends, and the occasional defective board. Diagonal or picture-frame layouts need more.
- Does this include joists, posts, and fixings?
- This estimates deck boards. Create a free BuilderBuddi account to build the full deck estimate with joists, posts, fixings, and labour.
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