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.
Your home extension details
Approximate added floor area in square metres.
Your estimate sits within the typical range.
Your estimate sits within the typical range.
Where the money goes
Estimated breakdown for your configuration
Site access, slope and connecting to existing services can add tens of thousands, get a site assessment early.
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.
How we estimate this
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: October 2026.
Home extension prices by city
Costs vary by city. See the local breakdown for your capital.
Doing more than just home extension?
Build a combined estimate across every part of your project in one place.
Pricing reviewed October 2026. Indicative Australian costs, not a quote.
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.
Are you a renovation business?
Everyone on this page is working out what home extension costs because they are ready to hire. Put your business right beneath the calculator, in your state, so you are who they find. From $200/mo.