Decking Calculator

Calculate decking boards needed for an outdoor deck.

Fill in the fields below to calculate

Deck Length (m)

Deck Width (m)

Board Width (mm)

Board Length (m)

Gap (mm)

Enter your values above and tap Calculate to see the result.

Your Results

Total Boards Needed (inc. 10% waste)

Boards Per Run

Number of Runs

Formula

Boards per run: = ⌈W × 1000 / (board_w + gap)⌉

Runs: = ⌈L / board_length⌉

Total: = boards_per_run × runs × 1.1 (waste)

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Pro Tips

Results update as you type — change any field to see the effect immediately.

Check that every value uses the same unit before comparing results.

Use the copy button to paste the decking figures into a note or spreadsheet.

Nothing is sent to a server, so you can use this with private figures.