The question of what a house is worth sounds simple. The process behind answering it is not. Knowing what sits behind a property valuation changes how a seller reads the number they are given and how they respond when buyers push back on it.
How Property Value Is Determined
Property value is not a fixed figure sitting in a database somewhere waiting to be retrieved. It is built from comparable sales data, adjusted for what makes the subject property different from those sales, and shaped by the market conditions at the time of assessment.
The most common method used by agents is the comparable sales approach. The agent selects recent sales that most closely resemble the property being appraised and adjusts the estimated value based on the differences - a larger block, a newer kitchen, a busy road frontage.
The expectation that a skilled agent will identify the one true value of a property is understandable but inaccurate. Which sales are most comparable, how much weight each one carries, and how to adjust for specific property features are all judgement calls, and reasonable practitioners make them differently.
The volume of recent sales in an area also affects how reliable any estimate can be. Where a suburb has high transaction volume and relatively uniform housing stock, the pool of comparable sales is deep and agent estimates tend to cluster more closely together. When the data is thin and properties differ substantially from one another, the interpretation gap between agents widens.
Why a Free Appraisal and a Bank Valuation Are Not the Same Thing
Treating a free agent appraisal and a formal property valuation as interchangeable is one of the more consequential misunderstandings sellers bring to the selling process. They are not.
The appraisal an agent delivers is their interpretation of what the market is likely to pay, based on comparable sales and their own market experience. It is produced to assist with the listing decision and is not subject to independent verification or professional oversight. No legal standing attaches to an agent appraisal, and the agent providing it has a commercial interest in the relationship that follows.
The formal valuation process is regulated, conducted by a licensed practitioner, and produces a document that carries legal and financial weight in a way an agent appraisal does not. It costs money, takes longer, and produces a document rather than a conversation.
Sellers who conflate the two are making decisions based on a document that carries less weight than they assume it does. An appraisal is a starting point for a pricing conversation. A valuation is a defensible professional opinion with legal weight behind it.
For a closer look at what a property appraisal involves and what it tells you, see more for more on what to expect from a property assessment.
Not every seller needs to commission a formal valuation before going to market. Knowing what an appraisal is and is not puts a seller in a better position to evaluate what they are being told and ask the right questions about how the figure was reached. Agents who are comfortable with detailed questions about their methodology tend to be the ones with the strongest evidence behind their estimates.
What Automated Valuation Tools Cannot Tell You
The rise of automated valuation tools means any homeowner can get a number attached to their property inside thirty seconds. What those tools cannot do is produce an estimate that reliably reflects what a buyer would actually pay on the day.
Automated valuation models work by pulling recent sales data and applying statistical algorithms to estimate value based on property characteristics recorded in public databases. What they cannot access is interior condition, recent renovation work, presentation quality, or the specific features that make one property more or less appealing than another with identical specifications on paper.
An automated tool treating two identical-specification properties as equivalents is producing an estimate that the market would immediately disagree with. The market will treat those two properties very differently. The algorithm will not.
Used carefully, online estimates can give a homeowner a rough sense of where their suburb sits in the broader market. They are a poor substitute for a current market appraisal from an agent actively selling in the area.
How Adjustments Create the Appraisal Gap
When a seller approaches three agents for appraisals and receives three meaningfully different numbers, the natural assumption is that at least two of them must be wrong.
Three different appraisals of the same property produce the same question in almost every seller: which one is right.
The more accurate reading is usually that all three agents are working from legitimate interpretations of the same data. The comparable sales do not change between the three appraisals. What changes is how each agent reads them, weights them, and adjusts for the differences between those sales and the subject property.
The first agent places significant weight on a sale from four months prior that closely matches the subject property in their assessment. Another may discount that same sale because it occurred before a shift in buyer sentiment and lean instead on a more recent result at a lower price. A third practitioner may value a specific attribute more highly than the others and let that premium lift the overall estimate.
The spread between three appraisals on the same property is not evidence of incompetence. It confirms that property valuation is not arithmetic - it is judgement applied to evidence. What matters is not the size of the number but the quality of the reasoning behind it.
The conversation about methodology rarely happens, even though it is the most important conversation available to a seller at that stage. The ones who do are usually better positioned to set a realistic price and hold their nerve through the negotiation that follows.
For further reading on how the property market works and what recent results mean for sellers and buyers, see here for more context on how the market is moving.
How to Know What Your Property Is Worth - Common Questions
How do I find out what my house is worth
Getting an appraisal from an agent with recent sales in your suburb gives you the most current and directly relevant picture of what buyers are paying. An agent working recent sales in your area will have direct knowledge of what buyers are paying, how long properties are taking to sell, and what features are driving price differences between comparable homes. Online estimates provide a general range but should not be relied on for pricing decisions.
Why do online property estimates differ from agent appraisals
Online property estimates vary significantly in accuracy depending on the suburb, the volume of recent sales activity, and how recently the underlying data was updated. In suburbs with high turnover and consistent property types, automated estimates can be reasonably close to market value. In suburbs with lower volume, older stock, or significant variation between properties, the margin of error can be substantial. They are best used as a broad orientation tool rather than a pricing reference.
Is it worth getting a property appraisal before selling
Getting an appraisal before committing to selling is worth doing even if the decision to sell is not yet finalised. An appraisal converts the timing question from speculation into a decision informed by current market evidence. The appraisal process does not commit a seller to listing with the agent who provides it. Getting appraisals from two or three agents and understanding how each arrived at their estimate provides a more complete picture than relying on a single opinion.
Online tools tell you what an algorithm thinks. An appraisal tells you what the market evidence shows. Only one of those is useful when you are making a decision.