What our analysis shows
Analysis by Granny Flat Numbers, data as of 23 October 2026
- In Sydney the second bedroom adds $41,000 to the build (45 m² $179,000 against 60 m² $220,000). To pay that back in 10 years after tax it needs to earn about $125 a week more than a one-bedroom.
- Across 42 areas the median extra rent for a second bedroom was $130 a week. A two-bedroom flat gave the higher net yield in 35 of 42 areas.
- One bedroom wins where the step up to two bedrooms is small: Greater Sydney, South-west Sydney, Brisbane, City of Melbourne, Monash, Wyndham, Adelaide metro. Most are inner or well-connected areas where one-bedroom rents are strong.
- The biggest gains from a second bedroom were Newcastle, Townsville, Logan, where one-bedroom flats rent cheaply and two-bedroom homes rent close to house prices.
Where the second bedroom adds most to net yield
- Newcastle (NSW)+3.9 pts
- Townsville (QLD)+3.7 pts
- Logan (QLD)+2.8 pts
- Western Adelaide (SA)+2.8 pts
- Moreton Bay (QLD)+2.6 pts
- Cairns (QLD)+2.6 pts
- North-west coast (TAS)+2.4 pts
- Launceston (TAS)+2.1 pts
Net yield of a 60 m² 2-bed minus a 45 m² 1-bed, each on its own build cost and local median bond rent.
What the second bedroom costs
| Sydney, standard finish | Total | Per m² |
|---|---|---|
| Studio, 35 m² | $154,500 | $4,410 |
| 1 bed, 45 m² | $179,000 | $3,980 |
| 2 bed, 60 m² | $220,000 | $3,670 |
The second bedroom costs less than its share of the floor area suggests. Site work, connections, approval and design are the same for both sizes, and the kitchen and bathroom are already paid for. That is why the cost per m² falls as the flat grows.
Area by area
| Area | Extra rent, 2nd bed | Net yield 1 bed | Net yield 2 bed |
|---|---|---|---|
| Newcastle (NSW) | $240 | 10.5% | 14.4% |
| Townsville (QLD) | $200 | 9.1% | 12.8% |
| Western Adelaide (SA) | $195 | 10.4% | 13.1% |
| Moreton Bay (QLD) | $185 | 8.3% | 10.9% |
| Logan (QLD) | $185 | 7.6% | 10.3% |
| Cairns (QLD) | $180 | 12.4% | 14.9% |
| Hills and north-west (NSW) | $160 | 11.0% | 12.2% |
| Darebin (VIC) | $160 | 10.6% | 12.2% |
| Casey (VIC) | $160 | 8.3% | 10.3% |
| Southern Adelaide (SA) | $153 | 10.6% | 12.3% |
| Sunshine Coast (QLD) | $150 | 12.9% | 13.8% |
| Merri-bek (VIC) | $150 | 11.4% | 12.6% |
| Launceston (TAS) | $145 | 10.4% | 12.5% |
| North-west coast (TAS) | $145 | 8.7% | 11.1% |
| Wollongong (NSW) | $140 | 12.3% | 13.4% |
| Rest of NSW (NSW) | $140 | 9.9% | 11.5% |
| Knox (VIC) | $140 | 10.1% | 11.4% |
| Northern Adelaide (SA) | $140 | 9.4% | 11.0% |
| Gold Coast (QLD) | $135 | 16.1% | 16.2% |
| Eastern Adelaide (SA) | $133 | 13.5% | 14.2% |
| Central Coast (NSW) | $130 | 11.1% | 12.2% |
| Ipswich (QLD) | $130 | 9.1% | 10.3% |
| Toowoomba (QLD) | $130 | 10.0% | 11.7% |
| Whitehorse (VIC) | $130 | 11.4% | 12.2% |
| Brimbank (VIC) | $120 | 8.0% | 9.2% |
| Regional SA (SA) | $120 | 7.5% | 9.5% |
| Frankston (VIC) | $115 | 9.6% | 10.3% |
| Western Sydney (NSW) | $110 | 10.2% | 10.5% |
| Hume (VIC) | $110 | 8.6% | 9.4% |
| City of Melbourne (VIC) | $108 | 14.9% | 14.4% |
| Whittlesea (VIC) | $105 | 9.3% | 9.9% |
| Greater Sydney (NSW) | $100 | 12.8% | 12.4% |
| Greater Geelong (VIC) | $100 | 9.7% | 10.6% |
| Greater Bendigo (VIC) | $100 | 10.0% | 10.9% |
| Monash (VIC) | $94 | 12.7% | 12.4% |
| Greater Hobart (TAS) | $93 | 11.1% | 11.1% |
| Redland (QLD) | $90 | 10.0% | 10.1% |
| Adelaide metro (SA) | $89 | 12.9% | 12.6% |
| Ballarat (VIC) | $82 | 8.0% | 8.7% |
| South-west Sydney (NSW) | $60 | 10.0% | 9.3% |
| Brisbane (QLD) | $60 | 15.4% | 13.8% |
| Wyndham (VIC) | $0 | 10.6% | 8.5% |
Each flat on its own build cost for the state (regional rate outside capitals) and the median bond rent for the area. Rents are for detached dwellings in NSW and Tasmania, and one-bedroom flats and two-bedroom houses elsewhere.
Where one bedroom wins
In 7 areas the one-bedroom flat earned the better yield. What they share is a small step up from one to two bedrooms. In Greater Sydney, for example, the second bedroom added only $100 a week. If you are in an inner suburb near transport or a hospital or university, check one-bedroom rents first; a smaller flat also leaves more of your yard.
Studios
A 35 m² studio costs about $154,500 in Sydney, only $25k less than a one-bedroom. Studio rents are thin in bond data because few studios are detached. For a rental, a one-bedroom with a separate bedroom almost always earns the difference back. A studio makes sense for a home office, a teenager or a guest room where rent is not the point.
If the flat is for family
For an ageing parent, a second bedroom gives room for a carer to stay overnight, and later makes the flat easier to rent. For an adult child, two bedrooms let them share costs with a partner or flatmate. If the flat will be family housing first and a rental later, two bedrooms are usually the safer choice. See a granny flat for your parents.
This week's worked example
Week of 19 October 2026. A new example, rule and owner report every Monday.
A 55 m² two-bedroom flat with a budget finish on a block with some slope, services 15 m from the house, in Brisbane: our model puts it at $172,000 turnkey ($151,000–$192,500), or $3,120 per m². At the area's median 2-bedroom bond rent of $650 a week it would return 16.1% net and pay back in 8.4 years after tax.
Rule check: In NSW's July–September 2026 bonds, Western Sydney detached one-bedroom dwellings rented for a median $450 a week against $580 for one-bedroom flats.
From an owner (NSW, 2023): A seven-year-old, council-approved 60 m² brick two-bedroom flat in Western Sydney was rented for $400 a week, according to the selling agent.
Questions people ask
Is a one or two bedroom granny flat better?
For renting, two bedrooms gave the better net yield in 35 of the 42 areas we tested. One bedroom wins where tenants pay little extra for the second bedroom, such as Greater Sydney, South-west Sydney, Brisbane.
How much more does a two bedroom granny flat cost?
About $41,000 more in Sydney for 60 m² instead of 45 m², with the same finish. Per square metre the larger flat is cheaper, because the kitchen, bathroom and connections are shared costs.
Can a 60 m² granny flat have two bedrooms?
Yes, comfortably, with one bathroom, an open kitchen and living area and a small laundry. Most NSW granny flat designs at the 60 m² limit are two-bedroom.