Granny Flat Cost Calculator & Price Guide
Use this Granny Flat Cost Calculator & Price Guide to get a clearer idea of granny flat cost in Australia, whether you are comparing a prefab granny flat, portable granny flats or a more customised build. Based on the standard pricing here, granny flat prices range from $110,000 AUD for a studio portable/prefab model up to $210,250 AUD for a 2 bedroom brick/custom option.
Estimate granny flat build cost
Turnkey-style midpoints for Australia. Pick size and build path. Slab, service connections, council approvals and landscaping are usually extra ($15k–$50k all-in).
Estimates are indicative only. For an accurate price, get free quotes from local tradies above.
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Granny Flat Price Breakdown
Typical job based on 1 granny flat (Portable / prefab). Prices are supply-and-install midpoints — actual quotes will vary.
| Type | Cost per granny flat (Portable / prefab) | Typical 1 granny flat (Portable / prefab) job |
|---|---|---|
| Studio | $110,000 | $110,000 |
| 1 bedroom | $125,000 | $125,000 |
| 2 bedroom | $145,000 | $145,000 |
What Affects Granny Flat Cost?
- Size and bedroom layout: The biggest driver of granny flat build cost is the layout you choose. Portable/prefab pricing starts at $110,000 AUD for a studio, rises to $125,000 AUD for a 1 bedroom, and reaches $145,000 AUD for a 2 bedroom granny flat.
- Build type: The construction method changes the final cost for granny flat significantly. Portable/prefab uses the base rate, site-built turnkey is priced at 1.25 times the base, and brick/custom is 1.45 times the base.
- Level of customisation: Granny flats prefabricated and standard portable designs are usually the most budget-friendly because they follow set plans and sizes. Moving to a site-built or brick/custom option generally increases granny flat construction cost because of the higher multiplier applied to the same base model.
- Estimate range and minimum pricing: Displayed estimates use a range of plus or minus 15% around the midpoint, so your quote will usually appear as a range rather than one fixed figure. There is also a minimum job charge of $80,000 AUD, although the listed granny flat models here all sit above that threshold.
Granny Flat Cost - Frequently Asked Questions
Using the pricing in this calculator, a portable/prefab granny flat starts at $110,000 AUD for a studio, $125,000 AUD for a 1 bedroom, and $145,000 AUD for a 2 bedroom. If you choose site-built turnkey, those same layouts are $137,500 AUD, $156,250 AUD and $181,250 AUD. For brick/custom, pricing increases to $159,500 AUD, $181,250 AUD and $210,250 AUD.
For a typical job of 1 granny flat, the starting point depends on the layout and build type. A 1 bedroom portable/prefab model is $125,000 AUD, while a 1 bedroom site-built turnkey version is $156,250 AUD and a brick/custom version is $181,250 AUD. This makes the 1 bedroom format a common reference point when comparing granny flat prices.
Portable/prefab pricing is $110,000 AUD for a studio, $125,000 AUD for a 1 bedroom, and $145,000 AUD for a 2 bedroom. Site-built turnkey pricing is $137,500 AUD, $156,250 AUD and $181,250 AUD for those same layouts. Brick/custom pricing is $159,500 AUD, $181,250 AUD and $210,250 AUD.
Yes, a prefab granny flat is cheaper in this pricing model because portable/prefab uses the base rate, while site-built turnkey uses a 1.25 multiplier. For example, a 2 bedroom portable/prefab granny flat is $145,000 AUD, compared with $181,250 AUD for site-built turnkey. That same 2 bedroom design rises further to $210,250 AUD in brick/custom form.
The calculator applies a 1.45 multiplier for brick/custom builds. That means a studio is $159,500 AUD, a 1 bedroom is $181,250 AUD, and a 2 bedroom is $210,250 AUD. This is the highest-cost pathway in the current granny flat construction cost guide.
Yes, portable granny flats and granny flats prefabricated are priced using the same base rates in this calculator. The base pricing is $110,000 AUD for a studio, $125,000 AUD for a 1 bedroom, and $145,000 AUD for a 2 bedroom. Estimate ranges are then shown at plus or minus 15% around those midpoint figures.
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