Decking Calculator

How it works

The tool divides the deck width by the combined width of one board plus its adjacent gap, which gives the number of board rows needed. Multiplying the rows by the deck length yields the total running metres.

For instance, a 120 mm board with a 5 mm gap takes up 125 mm across, so a wide deck needs surprisingly many rows.

Inputs and results

Enter the deck length and width in metres, plus the board width and gap in millimetres. You get the number of board rows, the running metres and the deck area.

The headline figure shows the running metres with a 10% waste margin already added, so you can order boards directly.

Who it is for

It is useful when building or replacing a deck and planning your yard work. It helps you estimate material costs before a trip to the hardware store.

Tips

Run the rows across the deck width. Add 10% waste for cuts, since board ends often have to be sawn and joints consume material. Also check the real board width, as it directly affects the number of rows.