Last reviewed September 2026 by Megan Birot, Content Editor, OurTop10. Figures checked against the sources named in the article.A property value estimate is a computer’s best guess at what your home would sell for today, built from recent sales of similar homes nearby. The free ones from the big data companies are usually within about 10% of the eventual sale price for an ordinary house in an ordinary suburb, and a long way out for anything unusual. That 10% on a $1 million home is $100,000, which is why the estimate is a starting point and not a number to borrow against.
This guide covers how the estimates are built, how far to trust them, the three other ways to get a figure and what each one costs, and how to sanity-check any estimate yourself using the comparable sales method valuers actually use. There is a tool further down the page that does the comparable-sales sum for you.
How a property value estimate is calculated
Every free online estimate comes from an automated valuation model. It takes the property’s recorded attributes (land size, bedrooms, bathrooms, car spaces, build date), finds recent sales of similar properties within a radius, adjusts for the differences it can measure, and prints a range. Cotality (the company formerly called CoreLogic), PropTrack and Domain each run one, and most bank and broker “property reports” are one of those three with a different logo on top.
What the model can see: the sales record, the land size, the number of rooms, the street, the suburb’s recent price movement. What it cannot see: the renovated kitchen, the rising damp, the view, the main road out the front, the block next door about to become a childcare centre. Those are the things that move a sale price by $50,000 or more, and they are why two houses the model prices identically can sell $200,000 apart.
How accurate the free estimates are
For a standard house or unit in a suburb with plenty of sales, expect the estimate to land within about 10% of the eventual price either side, and the range around it to be honest about that. Accuracy drops fast when there is little data: acreage, unusual homes, new suburbs, apartments in a building with no recent sales, or anywhere the market has moved sharply in the last six months, because the model is looking backwards at sales that settled months ago.
The practical test is the confidence band. A tool that says $920,000 with a range of $870,000 to $970,000 is telling you it has good data. A tool that says $920,000 with a range of $750,000 to $1.1 million is telling you it is guessing, and the midpoint means little.
James Haywood
Financial Services Expert
“Online property estimates are a helpful starting point, but they should never be treated as the final answer. Two homes on the same street can achieve very different results depending on renovations, layout, presentation and buyer demand.
From a lending perspective, the valuation that matters most is often the one completed for the bank. That figure can impact your available equity, loan options and even whether your finance approval proceeds as expected.”
James Haywood – Director | Approved Finance
The four ways to get a figure, and what each costs
| Method | Who does it | Cost | Use it for |
|---|---|---|---|
| Online estimate | Automated model | Free | A first idea, tracking your equity over time |
| Agent appraisal | Real estate agent, on site | Free | Deciding whether and when to sell. Get three, ignore the highest |
| Bank valuation | Independent valuer for the lender | Usually free to the borrower | The only figure that counts for a loan, a refinance or an equity release |
| Formal valuation | Certified valuer, written report | $300 to $600 | Family law, estates, tax, disputes, buying out a co-owner |
The agent appraisal is free because the agent wants the listing, and some inflate the number to win it. Ask three agents, ask each to show you the three sales they based it on, and treat the highest figure with suspicion.
The bank valuation is the one that decides your borrowing. Lenders order it, a valuer they choose completes it, and the loan is measured against that figure rather than the price you paid or the estimate you found online. In suburbs where prices have softened since 2024, bank valuations are coming in below owners’ expectations often enough that brokers now run a desktop check before lodging an application. A low valuation on your file is harder to argue with than no valuation at all. Our guide to property valuation goes through what the valuer looks at.
The formal valuation is a paid, signed report that stands up in court and with the tax office. You need it when the number has legal weight: a separation, a deceased estate, transferring a share to a family member, or setting a cost base for capital gains tax.
The free estimate tools, and what each one asks for
- Cotality property value (the former CoreLogic): the model behind most bank reports. Asks for an email.
- realestate.com.au property estimate (PropTrack): strong on recent listings and sales. Free with a login.
- Domain Home Price Guide: a range plus recent comparable sales you can check yourself.
- NAB, Lendi and Aussie property reports: Cotality or PropTrack data behind a lender’s front page, usually in exchange for your phone number and a follow-up call.
Run two of them, not one. If they agree within 5%, you have a usable figure. If they disagree by 15%, the property is one the models cannot read, and you need a person to look at it.
How to check an estimate yourself: the comparable sales method
This is what a valuer does, and you can do a rough version in twenty minutes. Find three to five sales in the last six months, within a kilometre, of properties as close to yours as possible in land size, bedrooms and condition. Then adjust each one for the differences: add for what yours has that the sale did not, subtract for what it had that yours does not. A rough rule for suburban Sydney or Melbourne is $30,000 to $60,000 per bedroom, $15,000 to $30,000 per bathroom or car space, and 10% to 15% for a full renovation versus original condition. Average the adjusted figures and you have an estimate that is usually tighter than the free tools, because you can see what they cannot.
The estimator below does the arithmetic. It will not know your street, but it will show you how much each assumption moves the answer, which is the point.
Comparable sales value estimator
Find three recent sales of similar homes in the same suburb, enter the price and internal size of each, then the size of the property you are valuing. The tool works out a price per square metre and gives a range.
| Comparable sale | Sale price ($) | Internal size (sqm) | Condition vs yours |
|---|---|---|---|
| Sale 1 | |||
| Sale 2 | |||
| Sale 3 |
Built by OurTop10. Results are estimates for comparison only and are not credit advice. Figures stay in your browser and are not sent anywhere.
Andrew Hadjidemetri
Financial Services Expert
“A property valuation is more than just knowing what your home could sell for. For homeowners looking to refinance or invest, the valuation can directly influence borrowing capacity and the strategies available.
A stronger valuation may open up opportunities to access equity or secure a more suitable loan structure, while a lower-than-expected valuation means you may need to adjust your approach before making your next move.”
Andrew Hadjidemetri – Director | Australian Financial & Mortgage Solutions
What the estimate changes, depending on what you are doing
Selling. The estimate sets your expectation, the appraisals set the price guide, and the market sets the price. If the three agents and the two tools all land within 5% of each other, list there. If they spread across $150,000, the property is hard to price and an auction may do the work the tools cannot.
Buying. Run the estimate on the property you are bidding on, then run the comparable sales yourself. If the guide price sits well above both, the agent is quoting hope. If your pre-approval assumed a lower price than the estimate, the lender’s valuation is the figure that will decide what you can pay, not the estimate; our guide to pre-approval covers how that plays out at settlement.
Refinancing or releasing equity. Lenders will usually let you borrow up to 80% of their valuation. An estimate $50,000 higher than the bank’s figure is $40,000 of equity you thought you had and do not. Have a broker order a desktop valuation before you apply, and if it comes in low, wait rather than lodge. Our guide to cash-out refinancing works through the numbers.
Investing. The estimate matters less than the rent and the growth history. Check the suburb’s five-year price movement and the current yield before you check the value, and read our guide to investment property for the rest of the sum.
What to do next
Run two free estimates, then the comparable sales method above, and keep whichever figure the three agree on. If the number is for a loan, the only figure that counts is the lender’s, and a broker can order a desktop valuation before you commit to anything. Our ranked broker lists for Sydney, Melbourne and Brisbane are reviewed regularly.
FAQs
How accurate is a property value estimate?
For a standard home in a suburb with plenty of recent sales, usually within about 10% of the sale price either way. Accuracy falls sharply for unusual properties, acreage, new suburbs and buildings with few sales, and whenever the market has moved quickly in the last six months.
Is an online estimate the same as a valuation?
No. An estimate is a computer model working from public records. A valuation is a licensed valuer who has inspected the property and signed a report. Lenders act on valuations, not estimates.
How much does a property valuation cost?
A formal valuation with a written report is usually $300 to $600 for a standard home. A bank valuation ordered for a loan is normally free to the borrower. Agent appraisals are free.
Why is the bank’s valuation lower than my estimate?
Valuers are paid to be conservative because the lender wears the loss if you default, and they are looking at settled sales that are two to four months old. In a softening market that lag pulls the figure down. It can be challenged with better comparable sales, but rarely moves more than a few percent.
How often should I check my property’s value?
Once or twice a year is enough for most owners, and always before refinancing, releasing equity or selling. A valuation report is generally treated as current for about 90 days.
Which free property estimate is the most accurate?
None is consistently best. Cotality, PropTrack and Domain each have suburbs where their data is thicker. Run two and compare the ranges; if they agree within 5% you have a figure you can use.
Mansour Soltani
Head of Research, OurTop10
With over two decades of experience in Australia’s real estate sector, Mansour has built a career specialising in the acquisition and sale of investment and commercial properties, spanning major metropolitan hubs and regional areas. As the founder and owner of a finance brokerage firm, he manages a loan portfolio exceeding $200 million while serving a broad range of clients nationwide.
A frequent contributor to money.com.au, Mansour has developed a deep understanding of diverse investment strategies, enabling him to provide valuable, well-informed perspectives on market trends and opportunities.