Understanding the estimate

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This calculator gives you an indicative cost range based on current 2026 NSW construction market data. Select your project type, floor area, finish level, number of storeys, and site complexity. Your estimate updates instantly and can be downloaded to share with us or your builder.

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The figures produced are construction costs only. They're intended as a planning guide — not a contract figure. We always recommend obtaining a minimum of three independent builder quotes before committing to any construction contract.

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What the calculator covers

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Project types: The calculator covers three residential project types. New builds are priced from a clean site with no existing structure. Renovations reflect the higher per-m² cost of working within an existing building, including the complexity of sequencing work around existing services, structure, and layout. Extensions sit between the two — new floor area is added, but the existing building introduces constraints.

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Finish levels: Basic covers project-grade fittings, standard cabinetry, and entry-level flooring. Standard reflects quality mid-market construction with engineered stone benchtops, modern joinery, and quality tapware. High-end covers premium materials, custom joinery, bespoke detailing, and architect-specified inclusions.

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Number of storeys: Single storey is the baseline. Double storey adds an 18% premium reflecting upper floor framing, staircase construction, and additional structural engineering. Three or more storeys adds 35%, reflecting multi-level structural systems, increased compliance requirements, and greater construction complexity.

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Site complexity: Standard applies to flat or near-flat blocks with no significant constraints. Slightly sloping adds 7% for cut and fill or retaining requirements. Steep adds 15% for significant slope, difficult access, or complex footings. Heritage or complex adds 20% for heritage overlays, existing structures, or highly constrained sites.

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Cost breakdown

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When you run an estimate, the calculator also shows how your total cost typically breaks down across the six main construction categories.

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Structure and framing accounts for approximately 26% of construction cost — the slab or subfloor, wall frames, and roof structure, forming the primary structural system of the building.

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Fit-out and finishes represents around 25% and is where finish level has the most impact. Cabinetry, flooring, tiling, painting, and joinery all sit here.

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Mechanical systems — plumbing, electrical, and HVAC — typically account for 18%. These costs are largely fixed regardless of finish level and scale with building size and wet area count.

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Site works and foundations represent approximately 13% on a standard site, rising significantly on sloped, reactive, or constrained sites.

Windows, doors, and external works account for around 9%. Glazing specification and external cladding choices have considerable cost impact within this category.

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Professional fees — architecture, engineering, and project management — represent approximately 9% of construction cost. These are not included in builder quotes and should be budgeted separately.

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What's not included

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The calculator covers construction costs only. The following are not included and should be budgeted separately:

• Land purchase price and stamp duty

• Council fees, development application costs, and building permits — typically $5,000 to $30,000 depending on project scope

• Architecture and building design fees — typically 8 to 15% of construction cost

• Landscaping, driveways, and external works beyond the building envelope

• Furniture, appliances, and window furnishings

• Utility connections for water, gas, electricity, and NBN

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Add a minimum 15% contingency to your construction estimate. Construction projects regularly encounter unforeseen conditions — reactive soil, hidden services, structural surprises in renovations. Budget for it before you need it.

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NSW 2026 rates

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Construction costs across NSW have risen significantly in recent years, and the calculator applies current 2026 market data specific to the state. Within NSW, inner metropolitan Sydney typically carries a 10 to 20% premium over outer suburban and regional areas.

Common mistakes when budgeting a build or renovation

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Budgeting only for construction and forgetting associated costs is the most common planning mistake. Design fees, council approval, permits, landscaping, and contingency typically add 25 to 40% above the construction cost alone.

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Using outdated cost data is another common issue. Australian construction costs are 47% higher than pre-pandemic levels and have not returned to pre-2020 pricing. Figures from 2022 or 2023 will underestimate your current project cost significantly.

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Treating a single quote as the budget is a third mistake. Builder pricing varies considerably. Detailed design documentation generates more comparable and more competitive quotes. Vague briefs generate wide pricing ranges and expensive variations.

Skipping the contingency is consistently the decision renovators regret most. Open up an existing building and it will hold surprises. Budget for them before construction begins, not after.

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How to use this calculator

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Choose your project type — new build, renovation, or extension. Enter your floor area using the input field or the slider. Select your level of finish. Choose your number of storeys. Select your site complexity. Your estimate updates instantly across all three output fields.

To save your estimate, click Download / Print Estimate. The report includes your selected inputs and the full cost breakdown, ready to share with us or your builder.

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For a personalised estimate based on your specific brief and site, get in touch — we'll walk you through what's achievable for your project and budget.

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Planning today. Building tomorrow.

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An accurate cost estimate is a starting point — not a finished budget. Construction costs vary based on your specific site, your brief, the quality of your documentation, and the builder you select. Our team can help you design a project that's buildable within your budget, produce documentation that generates competitive quotes, and guide the process from concept through to completion.

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WE.DVLP is a Sydney-based building design studio creating considered residential and multi-residential spaces with clarity, creativity and technical precision.

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