The calculator returns whole rows, board pieces and total linear metres to order.
Home & Construction calculator
Decking Calculator
Enter the rectangular deck size, board dimensions and planned gap for a compact preliminary material count.
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No account. Formula and assumptions are shown below.
Calculator inputs
Decking boards details
Formula & disclaimer
Rows = Ceiling(Deck Width Γ· (Board Width + Gap)); Pieces per Row = Ceiling(Deck Length Γ· Board Length)
View assumptionsFormula reviewCalcs at Hand Editorial TeamVerified 31 August 2026 Β· automated checks included
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Resultβ
Projection
Move across the chart, drag the slider, or use the arrow keys.
Formula & details
Calculation
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How to read this result
Three useful checks, kept deliberately short.
A 6 m Γ 4 m deck using 3 m Γ 140 mm boards with 5 mm gaps: Calculate board rows Β· Calculate pieces per row Β· Add the waste allowance.
Joists, picture framing, diagonal layouts, board-end gaps and structural design are not included.
Formula and assumptions
Rows = Ceiling(Deck Width Γ· (Board Width + Gap)); Pieces per Row = Ceiling(Deck Length Γ· Board Length)This estimate assumes boards run along the entered deck length.
Keep in mind: Confirm span tables, joist spacing, fastening, ventilation and local structural requirements.
Produced byCalcs at Hand Editorial Team
Last formula check31 August 2026
Review methodKnown examples + boundary cases
Editorial and correction policy β