Estimate a deck.

What this calculator works out

This tool estimates a construction cost range for a timber or composite deck from three inputs: the deck area, how high it sits above the ground, and the decking material. It is meant for early planning — sizing up a rough budget before you have drawings or a builder's quote — not a substitute for a site measure.

Height above ground matters more than most people expect. A deck close to the ground is largely a surface-and-joist job, but once height increases, the substructure has to work harder and a balustrade is usually required, both of which the estimate accounts for automatically based on your answer.

Area sets the baseline cost, since material, framing and labour all scale with the surface being built, but area alone rarely explains the variation you'll see in real deck quotes — height and material usually do more of that work. A low deck needs a straightforward frame and footings; a high deck needs deeper footings, more bracing, and once it crosses a typical threshold, a balustrade under the building code, which this calculator adds as a separate allowance based on an estimated perimeter.

Material changes both the rate per square metre and the expected lifespan. Treated pine is the most affordable and widely available option; hardwood costs more but is harder-wearing and needs less frequent refinishing; composite decking costs the most upfront in exchange for very low ongoing maintenance. None of these are wrong choices — they trade differently between upfront cost and years of upkeep.

This estimate assumes a fairly standard rectangular deck shape. An irregular footprint, multiple levels, or built-in features like seating or planters will move the real cost above what a simple area calculation suggests, so treat a complex shape as a reason to check in with a builder earlier rather than later.

Nothing you enter here is sent anywhere or linked to your identity — your answers stay in your browser until you choose to carry them into a quote request, and you can come back and adjust any of the three inputs at any time before then.

As with the other calculators on this site, this one is meant to save you time, not replace a conversation with a builder once you're ready to compare quotes.