Decking Calculator

Calculate how many decking boards you need for any deck size, including board gap spacing and 10% wastage allowance.

Deck length (m)

Deck width (m)

Board width (including gap)

Board length

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Fill in the details to get your calculation.

Decking oil extends board life and maintains colour — apply every 12 months.

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How This Is Calculated

Boards run the length of the deck. Number of runs = deck width divided by board-plus-gap width. Each run may need one or more lengths of board depending on how the deck length relates to board length. Always add 10% wastage for cuts and defects.

All softwood decking should be treated annually with decking oil or stain — this prevents greying, splitting and cracking. Apply in dry weather when temperature is above 10°C. Sand lightly between coats for best finish. Hardwood decking (such as balau or iroko) needs less frequent treatment but still benefits from annual oiling.