Decking calculator
Your deck
A rectangle against the house. Change any figure, then choose what to work out.
The three deck calculators
Each one runs the same engine as the free deck designer, on the server, so it works on any phone.
Decking board calculator
How many deck boards, rows and clips or screws your deck needs.
Deck joist calculator
The joist spacing your boards allow, then the joists, bearers, posts and footings.
Composite decking cost calculator (per m², by state)
What the boards cost for your deck, at each board’s average price in your state.
How the figures are worked out
Every calculator describes a rectangular deck against the house, the designer’s Basic template, and runs it through the engine on the server: the board layout (rows across the deck, pieces and the fixings per crossing) comes from the chosen board’s cover width, gap and maximum joist centres; the framing (joists, bearers, posts and footings) from the engine’s framing rules and span tables.
Those span tables have been checked by a structural engineer. Every framed figure is still a concept figure, and every page says so: concept plan, not for construction. Have a builder, building surveyor or certifier check any design before you build it.
The cost calculator applies each board’s average price in your state to the deck’s area (the national average, labelled, where no seller there prices a board): board cost only, inc GST, with how many sellers each average comes from and how recent it is. Coverage is always stated and sample data is badged.