Investment Property Calculator Australia: Model Your Returns Before You Buy
The difference between a profitable investment property and a costly mistake often comes down to the numbers you run before making an offer. Too many investors rely on gut feeling or back-of-the-envelope maths when evaluating a purchase. A few minutes with the right calculators can reveal whether a property will generate positive cashflow, what your true upfront costs will be, and how depreciation can improve your after-tax position.
This guide walks through five free investment property calculators, explains when and how to use each one, and shows how they all fit together using a real worked example.
The Five Calculators Every Property Investor Needs
1. Cashflow Calculator
What it does: Estimates your weekly and annual cashflow by comparing rental income against all ownership costs, including mortgage repayments, council rates, insurance, property management fees, maintenance, water charges, and strata levies.
When to use it: Before making an offer on any investment property. Cashflow is the single most important number for determining whether a property will cost you money each week or put money in your pocket.
Quick example: A property renting for $500/week with total expenses of $2,300/month produces positive cashflow of approximately $167/month, or about $38/week. That is before tax deductions are factored in.
Try it: Cashflow Calculator
2. Rental Yield Calculator
What it does: Calculates both gross and net rental yield as a percentage of the property's purchase price. Gross yield uses rental income only, while net yield subtracts all holding costs.
When to use it: When comparing multiple properties across different price points and locations. A $400,000 property returning $400/week in rent has a very different yield profile to a $700,000 property returning $550/week, and yield percentage makes that comparison instant.
Quick example: A $650,000 property earning $550/week in rent has a gross yield of 4.4%. After expenses of $12,000/year, the net yield drops to approximately 2.5%. Understanding the gap between gross and net yield is critical for accurate modelling. See our full guide on how to calculate rental yield in Australia.
Try it: Rental Yield Calculator
3. Stamp Duty Calculator
What it does: Calculates the stamp duty (transfer duty) payable on a property purchase in any Australian state or territory. Each state has different rates, thresholds, and concessions for first home buyers, owner-occupiers, and investors.
When to use it: When budgeting your total upfront costs. Stamp duty is often the single largest expense after the deposit itself, and many first-time investors underestimate it. For a detailed breakdown of rates across every state, see our stamp duty guide.
Quick example: An investor purchasing a $650,000 property in Queensland pays approximately $13,650 in transfer duty. The same property in New South Wales would attract approximately $24,740 in duty. That $11,000 difference can significantly affect your return calculations.
Try it: Stamp Duty Calculator
4. Deposit Calculator
What it does: Calculates the total upfront cash required to purchase a property, including deposit (typically 10% to 20%), stamp duty, conveyancing fees, building and pest inspections, and lenders mortgage insurance (LMI) if applicable.
When to use it: Before you start seriously searching for properties, to understand what price range is realistic for your available savings. Also useful for comparing the cost difference between a 10% and 20% deposit, factoring in lender's mortgage insurance.
Quick example: A $650,000 investment property in Queensland with a 20% deposit requires approximately $157,000 in total upfront costs ($130,000 deposit + $13,650 stamp duty + $3,500 conveyancing and inspections + assorted fees). With a 10% deposit, you need less cash upfront but will pay LMI of approximately $8,000-$12,000 on top.
Try it: Deposit Calculator
5. Depreciation Estimator
What it does: Estimates the tax depreciation deductions available on a property, covering both Division 40 (plant and equipment, such as carpets, blinds, and appliances) and Division 43 (capital works, the building structure itself). These deductions reduce your taxable income without costing you any actual cash.
When to use it: When comparing newer properties against older ones. A brand-new property or recent renovation can generate $8,000-$15,000 in depreciation deductions per year, which can turn a cashflow-negative property into a cashflow-positive one after tax. Older properties built before 1987 have limited capital works deductions. See our full depreciation guide for more detail.
Quick example: A property built in 2024 with a construction cost of $350,000 generates approximately $8,750/year in Division 43 deductions alone (2.5% of construction cost), plus $3,000-$5,000 in Division 40 deductions for fixtures and fittings.
Try it: Depreciation Estimator
Worked Example: A $650,000 Brisbane Investment Property
Let us bring all five calculators together with a realistic scenario. You are considering a 3-bedroom, 1-bathroom house in Redcliffe, Brisbane, listed at $650,000. It was built in 2018 and is currently tenanted at $550/week.
Step 1: Deposit Calculator
With a 20% deposit:
| Item | Cost | |---|---| | Deposit (20%) | $130,000 | | Stamp duty (QLD) | $13,650 | | Conveyancing | $1,500 | | Building and pest inspection | $700 | | Loan application fees | $500 | | Total upfront cash | $146,350 |
Your loan amount is $520,000.
Step 2: Rental Yield Calculator
- Gross yield: $550 x 52 / $650,000 = 4.4%
- Net yield (after $12,500 in annual expenses): ($28,600 - $12,500) / $650,000 = 2.5%
A 4.4% gross yield is solid for a Brisbane house. Anything above 4% in a capital city is generally considered healthy for residential property.
Step 3: Cashflow Calculator
| Item | Annual | Weekly | |---|---|---| | Rental income | $28,600 | $550 | | Mortgage repayments (6.1%, 30yr, $520k) | -$38,000 | -$731 | | Council rates | -$1,800 | -$35 | | Insurance | -$1,600 | -$31 | | Property management (7.7%) | -$2,200 | -$42 | | Maintenance | -$1,500 | -$29 | | Water rates | -$1,200 | -$23 | | Pre-tax cashflow | -$17,700 | -$340 |
The property is negatively geared before tax deductions. This is where depreciation becomes important.
Step 4: Depreciation Estimator
For a 2018-built property with an estimated construction cost of $320,000:
- Division 43 (capital works): $8,000/year
- Division 40 (plant and equipment): $3,500/year
- Total depreciation: $11,500/year
Step 5: After-Tax Position
If your marginal tax rate is 37% (income between $120,001 and $180,000), the combined deductions from negative gearing and depreciation significantly improve your position:
| Item | Annual | |---|---| | Pre-tax cashflow | -$17,700 | | + Interest deduction tax saving | +$11,600 | | + Depreciation tax saving | +$4,255 | | + Other deductions tax saving | +$2,330 | | After-tax cashflow | +$485 |
The property goes from costing $340/week out of pocket to generating a small positive return after tax. This is the power of running all five calculators together rather than looking at any single metric in isolation.
Common Mistakes When Using Property Calculators
Using asking price instead of purchase price. Always model at the price you expect to actually pay, not the listed price. Factor in your negotiation strategy.
Forgetting ongoing costs. Many investors only consider the mortgage and ignore rates, insurance, maintenance, management fees, and vacancy periods. Budget for 2-4 weeks of vacancy per year.
Ignoring stamp duty in return calculations. Stamp duty is a sunk cost that directly affects your total return on invested capital. Include it.
Not accounting for interest rate changes. Run your cashflow at the current rate, then test at 1% higher. If the property only works at today's rate, it may be riskier than you think.
Assuming 100% occupancy. Even in tight rental markets, allow for vacancy between tenants, typically 2-4 weeks per year.
Want the Full Picture?
These calculators give you the numbers, but a complete investment analysis also includes comparable sales data, suburb growth trends, risk assessment, and offer strategy. PropBuyAI combines all of this into a single AI-powered report for any Australian property.
Your first analysis is free. Create your account and paste in any realestate.com.au listing to get started.