The Free Granny Flat Cost Calculator
Most builders quote the kit price or lock-up price and rarely reveal the real number until you’ve signed. Use this free on-page tool to budget for what they leave out: council fees, sewer, electricity and site works.
Four Phases of Your Real Budget
A finished granny flat is far more than the build price. Here is where the money actually goes.
Preliminaries
Surveyors, soil tests, certifier or CDC fees, BASIX and typical council contributions by state.
Site Costs
Earthworks, water connection, sewer trenching, electrical metering and stormwater. The big variable on most blocks.
The Build
Finishes
- Preliminaries. Surveys, soil tests, certifier fees and state-based council allowances.
- Site costs. Earthworks, water, sewer, electricity meter and crane access.
- Build + finishes. Slab to lock-up, then kitchen, bathroom and fit-out.
- Build-type aware. Traditional, modular and kit DIY each priced differently.
How To Use This Estimator
Three steps to a realistic ballpark figure. Adjust the inputs below and your estimate updates instantly.
Choose your build type
Pick traditional on-site, modular transportable, or a kit DIY build. Each carries a different cost profile.
Input your square meterage
The tool applies roughly $2,300 to $3,800 per sqm turnkey, depending on finish level and build type.
Add the hidden variables
Pick your state, approval path, slope, sewer run and electrical connection. These move the total more than finish level alone.
Granny Flat Cost Calculator
Updated for June 2026 Australian cost bands. All calculations run in your browser: nothing is saved or sent anywhere.
Project details
Pick a layout preset or adjust each field to match your block and build plans.
Rental yield & finance (optional)
Line-item estimate
| Item | Allowance |
|---|---|
| Certifier / CDC fees | $5,500 |
| State council contribution allowance | $9,000 |
| Earthworks, slab & access | $15,000 |
| Water connection | $2,500 |
| Electrical connection | $5,500 |
| Lock-up build (slab to roof) | $136,800 |
| Kitchen, bathroom & fit-out | $34,200 |
2026 cost bands by state
Typical turnkey ranges for a 60 sqm mid-finish granny flat. Your inputs may sit above or below depending on site works.
| State | Typical size rule | 60 sqm turnkey band (2026) | Approval timeline |
|---|---|---|---|
| NSW | 60 sqm common CDC cap | $175k–$240k | 3–8 weeks CDC |
| VIC | 60 sqm small second dwelling | $165k–$230k | 4–10 weeks |
| QLD | Code assessable in many zones | $160k–$225k | 4–12 weeks |
| WA | Up to 70 sqm in many metro lots | $155k–$220k | 6–12 weeks |
| SA | Planning and Design Code | $150k–$215k | 8–14 weeks |
| TAS | Council-dependent; reforms expanding | $155k–$220k | 8–16 weeks |
| ACT | Higher infrastructure levies | $185k–$260k | 10–16 weeks |
Got Your Ballpark? Take the Next Step
Use your estimate as a sanity check when you compare real quotes or dig deeper into the research.
Ready to Check Your Number Against Real Quotes?
Most homeowners use the calculator first, then compare two or three supplier quotes to see where the gaps are. It takes a couple of minutes and costs nothing.
Get matched with suppliersCross-check numbers, compatibility and local rules with official sources before you commit. Fee schedules, firmware requirements and council overlays change by state and postcode, so treat any single figure as a starting point. Use our tools and directories to compare options, then confirm with a licensed tradesperson, certifier or supplier before you sign.
Cost Calculator FAQs
Is the granny flat cost calculator free?
Yes. The calculator is free to use on this page with no sign-up and nothing to download. It gives general estimates only, not a fixed quote.
How accurate is the granny flat cost calculator for 2026?
It gives a reliable ballpark for June 2026, usually within 10–15% of a real quote when you are honest about site conditions. Council contributions, sewer distance and electrical connection move the total the most.
Does the calculator include council and CDC fees?
Yes. Preliminaries include certifier or CDC fees, surveys, BASIX and a typical state-based council contribution allowance. NSW Section 7.11 fees can range from $0 to over $20,000 depending on your council.
What is the average granny flat cost per square metre in Australia?
Most turnkey granny flats land between about $2,300 and $3,800 per sqm all-in once site costs and approvals are included. A mid-finish 60 sqm build often works out near $3,000–$3,500 per sqm in NSW and Victoria.
Does the calculator show rental yield?
Yes. Enter a weekly rent estimate and the tool calculates gross rental yield and a simple payback period against your all-in build cost. Treat this as a planning figure — vacancy, management and tax still apply.
How much does a 60 sqm granny flat cost in NSW?
A typical 60 sqm mid-finish granny flat in NSW often lands between roughly $190,000 and $220,000 turnkey once site works, sewer, metering and council fees are included. Steep blocks or long utility runs push higher.
Kit vs prefab vs custom — which is cheapest?
DIY kits usually have the lowest shell price but owner-managed trades and fit-out often close the gap. Prefab/modular sits in the mid band with faster timelines. Custom on-site builds cost more but suit odd blocks and premium finishes.
Do I need to download the calculator?
No. Everything runs in your browser. You can copy your summary or share a link with your inputs pre-filled. Nothing is stored on our servers.
