Decking Material Calculator

Estimate the number of decking boards and joists needed for a rectangular deck, including a 10% waste allowance.

Deck length (m)

Deck width (m)

Board length (m)

Board width (m)

Joist spacing (m)

How to Use the Decking Material Calculator

Enter deck length and width in metres.
Enter the length and width of the chosen board.
Enter joist spacing.
Click Calculate.

Casos de Uso

•DIY garden deck planning.
•Quick quotation for contractors.
•Material takeoffs for small builds.

Fórmula

Boards = ceil(deck_area / board_area × 1.10). Joists = ceil(deck_length / joist_spacing) + 1.

Perguntas Frequentes

Why 10% waste?

Ten percent is the typical allowance for cuts, end-matching and culling of defective boards on a straight rectangular deck. Complex shapes or diagonal patterns need 15–20%.

What joist spacing should I use?

Softwood decks use 400–600 mm centres; thermowood and composite boards often need 300–400 mm. Always follow the board manufacturer's span tables.

Does this include fixings?

No. Plan on roughly four screws per board per joist for hidden fasteners and two for face-fixed boards.