Free Investment Tool
Will a granny flat
pay for itself?
Run your own numbers in 30 seconds. Pick one of our three fixed-price builds, set your rent and loan terms, and watch the weekly cash flow, yield and payback update live — no email required.
Granny Flat ROI Calculator
Pick a build, drag the sliders, and see the cash flow update live. All figures are weekly unless noted.
Choose your build
Default is our appraised rent for this plan. Drag ±40% to match your suburb.
Investment construction loans are typically interest-only. Stress-test +1–2%.
Share of the build cost you pay in cash. The rest is borrowed.
Weekly outgoings
If your main house is also rented, adding a granny flat can shave a little off its rent. Model $0–$60/wk.
Your results
Positively geared$32,000
$22,000 deposit + $10,000 permits, soil test & connections allowance
$107/wk
on $88,000 borrowed at 6.3% p.a.
$217/wk
rent − repayment − outgoings − main-house adjustment
$11,273
18.0%
35.2%
2.8 years
$180,000 – $220,000
Bank valuers commonly add $180k–$220k for a compliant 30 m² self-contained dwelling in metro Melbourne — roughly 1.6–2.0× the build cost.
This calculator is illustrative only and is not financial, tax or credit advice. Figures are estimates based on E2ES fixed build prices, typical Melbourne rents and an interest-only loan structure; your rent, rate, fees, vacancy, tax position and valuation outcome will vary. Speak to your accountant, mortgage broker and a licensed financial adviser before committing to any investment.
Book a free feasibility chatFrequently asked questions
How accurate is this calculator?
The build prices are our real fixed prices and the default rents are our current appraisals for metro Melbourne, so the starting point is realistic. Your actual result depends on your suburb’s rent, your lender’s rate and fees, site costs and vacancy — treat the output as an indicative model, not a quote or a guarantee.
What interest rate should I use?
The default 6.3% p.a. reflects a typical interest-only investment construction loan. Use the rate your broker or lender has actually quoted you, and stress-test the result at 1–2% higher to make sure the cash flow still works if rates rise.
What is not included in the numbers?
The model excludes vacancy periods, repairs and maintenance, land tax changes, depreciation and other tax effects, and any loan setup or refinancing costs on your main mortgage. It includes a permits, soil test and services-connection allowance, but unusual site costs (rock, trees, long service runs) can add more.
Free Site Assessment
Start with a
30-minute site visit.
Tell us your address and which of the three plans you're drawn to. We'll review council overlays, confirm feasibility, and come back with a fixed-price quote, indicative rent and yield — all in writing, no obligation.
Sales & Feasibility
+61 485 903 388
hello@e2es.com.au
Office
Suite 631, Waterman Workspace, 44 Lakeview Drive, Scoresby VIC 3179