Home Extension Cost Calculator
Estimate a home extension in Australia. Enter the added floor area, choose single or double storey and finish level, then add inclusions like a new bathroom or kitchen.
Approximate added floor area in square metres.
Site access, slope and connecting to existing services can add tens of thousands, get a site assessment early.
- Framing & structure$25,050
- Internal fitout$22,550
- Slab & foundation$18,800
- Labour & management$18,800
- Roofing$15,050
- Windows & doors$12,550
- Services (plumbing/electrical)$12,550
💰 Ways to save
- Single-storey on a flat, accessible block is the cheapest way to add space.
- A simpler roofline and standard ceiling heights keep costs down.
or from $599/week over 5 years , indicative finance
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Home extensions in Australia are typically priced per square metre, about $2,400/m² for a basic single-storey addition to $4,500/m²+ for premium or double-storey work in 2026.
Pricing reviewed: June 2026.
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Understanding home extension costs in Australia
Home extensions in Australia are typically priced per square metre, about $2,400/m² for a basic single-storey addition to $4,500/m²+ for premium or double-storey work in 2026.
Adding a new bathroom or kitchen, demolition, and extensive glazing all add significantly to the base build. Site access and slope can also affect cost, so treat the estimate as a starting budget.
Frequently asked questions
How much does a home extension cost per square metre in Australia?
In 2026, single-storey extensions typically cost $2,400–$3,500/m² and double-storey $3,500–$4,500/m²+, depending on finish and site conditions.
Is it cheaper to extend or move house?
Extending avoids stamp duty, agent fees and moving costs. For many families a well-planned extension adds value above its cost, though this varies by suburb.
Do I need council approval for a home extension?
Most extensions need development approval or a complying development certificate. Requirements vary by state and council, your builder or a private certifier can advise.
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