Build Cost Calculator

How much does it cost to build in Sydney in 2026?

Build cost per square metre in Sydney metro for 2025–26 ranges widely depending on the type of dwelling, the level of finish, and the difficulty of the site. Our build cost calculator uses the following base rates (per square metre of gross floor area), with site-difficulty multipliers applied on top:

These rates are contract value figures — they include the builder's overhead and margin (when you sign a fixed-price contract). On a cost-plus contract you'd add a separate 15–25% margin line. They don't include land, stamp duty, council contributions, finance, HBCF, the architect, structural engineer, or contingency — all of which the calculator above adds for you.

What's included in build costs (and what's commonly missed)?

The biggest reason people get blindsided by their final build number isn't that their $/m² rate was wrong — it's that they forgot half the line items. PropDEV models every one of these:

• Construction — $/m² × GFA, with site-difficulty multiplier
• Builder margin — already in the rate on fixed-price; explicit 18% on cost-plus
• HBCF premium — NSW Home Building Compensation Fund (~0.7% of contract on residential builds > $20k)
• Architect & consultants — 4–12% of construction (architect, structural, civil, hydraulic, certifier, surveyor, energy, geotech)
• Professional fees — PM, DM, QS, accountant, insurance, body corp setup, strata legal (2–7.5% of construction)
• NSW DBP compliance — registered Design + Building Practitioners, regulated design declarations (~$45–120k on Class 2 builds)
• Council DA + s7.11 / s7.12 contributions — wildly variable, $8k–$75k per dwelling
• NSW stamp duty — 2025–26 schedule, premium band over $3.721M
• NSW land tax — 1.6% per year above $1.075M, 2% above $6.571M (almost no one knows this)
• Council rates — broken out as its own line ($1.5–4.5k/year Sydney metro)
• Buyer's agent fee — 1.5–2.5% of purchase or $15–40k fixed (if engaged)
• Finance — interest, line fees, establishment, capitalised onto the loan
• Marketing & selling — agent commission ~2.2% of GRV, marketing ~1.2% of GRV, legals
• GST under the margin scheme — 1/11 of (sale price − acquisition cost)
• Contingency & realism buffer — 3.5–10% by project stage plus an overrun buffer for things you priced that slipped anyway

NSW land tax — the silent line item

Many homeowners and developers don't realise NSW charges land tax annually on any land you own that isn't your principal place of residence — including development sites that are sitting waiting for DA approval or construction. The FY2025–26 schedule:

• Land value ≤ $1,075,000 — no land tax payable.
• Land value $1,075,001 – $6,571,000 — flat $100 plus 1.6% of the amount above $1,075,000.
• Land value over $6,571,000 — premium rate of 2.0% on the amount above $6,571,000, on top of the general band tax.

On a typical $3M Sydney development site that's about $31,000 per year while you hold it. On a $7M site it's about $97,000 per year. The calculator picks this up automatically from your purchase price (as a proxy for unimproved value) — toggle exempt if it's your PPR.

Class 1 vs Class 2 building — and why it matters

The National Construction Code classifies buildings into roughly ten classes. For residential developers in NSW, the two that matter are Class 1a (a single dwelling on its own title — e.g. a Torrens-titled duplex or detached house) and Class 2 (two or more sole-occupancy units sharing a building — almost every strata-titled duplex, townhouse, or apartment).

Class 2 (and Class 3 / 9c) trigger the NSW Design and Building Practitioners Act 2020: your builder must be DBP-registered, every regulated design needs a registered Design Practitioner's compliance declaration, and a Principal Design Practitioner coordinates the package. Practically that's an extra $45,000–$120,000 in fees plus 1.5–4 months of program — meaningful at duplex scale, very meaningful at townhouse scale.

The calculator's Building classification panel auto-detects Class 1a vs Class 2 based on your title type (Torrens vs strata) and yield, and adds the DBP compliance surcharge to the planning & design bucket when it applies. Override available.

Renovation cost calculator — should I add a bed & bath?

The Renovate / extend deal mode answers the homeowner question: “if I spend $X to add a bed and bath, what's my home worth after vs before — and am I better off?”

It uses the same cost engine as the developer side (construction, consultants, finance, contingency, HBCF, DBP where applicable) but the verdict is different: not “profit” but equity gain. The suburb median for the proposed bed-count config acts as your value ceiling — pushing your finished property materially above the suburb's median for that config is risky money, because buyers anchor hard to comparable sales.

Frequently asked questions