Inventory Levels – Measuring Months of Supply

The real estate market is always changing.

Inventory metric (also known as months of supply) is a major indicator of how healthy the market is in a suburb.

This metric helps real estate agents to understand whether or not they can expect more buyers to show interest in their listings.

In addition, the inventory metric serves as an excellent tool for property investors seeking to assess real estate market conditions prior to purchasing an investment property.

It builds on the Stock on Market metric by relating it to the average monthly sales volume.

Before you proceed with the remainder of this article, we recommend you review how the Stock on Market is calculated to fully understand the context.

What Changed in 2026

We’ve updated how the inventory metric is calculated. From the next data release onwards, the inventory formula uses accumulated stock on market rather than just new listings reported in the current calendar month.

Previously, the inventory metric only counted new listings entering the market within a given calendar month. The reason for this approach is documented in detail in our Stock on Market methodology article — it’s also why our standalone Stock on Market Percentage metric continues to use new listings only.

The reason we hadn’t applied the cumulative method to inventory before was historical. Our time series began shortly before the COVID-era boom, when surging demand consumed available stock across the country. A cumulative inventory measurement starting from that point would have been heavily skewed by the post-COVID drawdown — making the metric trends look artificially depressed for years.

Now that we’re well past that period in 2026, the cumulative method gives a far more accurate read on real supply conditions.

What This Means in Practice

Under the new formula, inventory now reflects the total stock sitting on the market at the end of each calendar month — current listings plus prior-month listings still active and unsold. Some sale listings can remain on the market for as long as six months before transacting, and the cumulative method captures that depth.

You’ll see two things in the updated charts:

• Higher headline values for inventory across the board. This is by design.
• A characteristic upward hump toward the end of the time series, as recent listings naturally accumulate before exiting the market through sale or withdrawal.

Importantly, this doesn’t break your analysis or filtering workflow. The recommended approach remains the same: combine inventory with the Stock on Market Percentage metric using a nested condition. Both Stock on Market Percentage trend and Inventory trend should be less than zero — those filtering rules continue to apply unchanged.

The threshold bands — favourable, neutral, and unfavourable inventory ranges — also remain as published in the HtAG Data Dictionary. Refer to those for interpretation.

And as before, the current month inventory value is reported as a three-month moving average, consistent with how we present current values for other metrics.

Why the Two Metrics Together Are More Powerful

Keeping Stock on Market Percentage on a new-listings basis and moving Inventory to cumulative gives you two complementary lenses on the same market:

• New Stock on Market Percentage shows the momentum — the volume of fresh stock entering the market each month, free from the accumulation hump.
• Inventory now shows the true depth — total active listings relative to monthly sales absorption.

Together, they paint the full supply picture. You can read both the incoming flow and the standing stock at the same time, which makes trend interpretation cleaner and conviction higher.

How to Interpret Inventory Levels?

Real estate agents frequently keep an eye out on the inventory metric in order to see if there’s been a recent increase or decrease.

This allows them to predict demand for new listings. So how exactly do we measure the inventory levels?

Lower inventory levels mean that buyers are buying more properties than real estate agents are putting on the market.

This is a good indication of an active real estate market, where property prices increase as demand exceeds the supply.

A higher inventory means fewer homes are sold.

This can point to a real estate market that is less competitive, where properties remain on the market for longer.

The lower the inventory, the tighter the supply is in the relevant property market.

The rule of thumb is that markets with 3 months or less of inventory levels present good ROI opportunities for property investors.

Inventory levels can also shed light on market seasonality.

In general, inventory levels rise during the spring when more homeowners list their properties, and they fall during the winter when real estate activity generally slows.

Changes in inventory levels can give investors insight into the market momentum.

For instance, if inventory levels are consistently decreasing, it could signal that the market is heating up and prices might increase in the near future.

Remember, inventory levels can vary significantly across different suburbs and property types (houses, units, townhouses, etc.), making it more important to delve into suburb-specific or property type-specific data.

In addition, from a seller’s perspective, understanding inventory levels can help form pricing strategies.

In a high inventory market, sellers may need to price competitively to attract attention away from the large pool of other listings.

Inventory Levels are a Lead Indicator for Price Movements

With the diminishing inventory levels, the Australian real estate market has become a sellers’ market in many capital cities and rural areas.

Common questions among investors now are: “Is it worth waiting it out because prices have peaked?

Or the prices will only increase from here on in, so there is no point in trying to ‘time the market’?”

The answer is: “It depends.”

There are sub-markets within markets.

Even though the overall trend is up, there are always pockets of real estate that are either lagging behind the general trend, or in some cases moving in the opposite direction.

As the inventory metric is a lead indicator for price movements, it’s important to measure whether it is increasing or decreasing compared to previous quarters.

Let’s illustrate the “multifacetedness” of the Australian real estate market.

You will notice that inventory levels differ quite significantly across the country today.

The chart below illustrates the inventory levels in Aussie suburbs country-wide.

Some suburbs have as low as 0.5 quarters (1.5 months) of inventory levels for houses.

Red markers to the right indicate the 95% quantiles of the distribution.

You should definitely avoid markets to the right of these red lines i.e. inventory levels of 2.5 quarters and above.

Summary

The inventory metric is an indispensable tool for property investors aiming to make informed decisions in the Australian real estate market.

It goes beyond simple supply measures, offering rich insights into the interplay between listings and sales activity.

Overall, while inventory levels are a significant factor in understanding the property market dynamics, they should be used in conjunction with other metrics for a complete market analysis and informed decision-making process.

No single metric exists in isolation and the interplay between various factors shapes property market behaviours and trends.

To summarise here are the key points for real estate investors to take away:

• HtAG measures inventory levels in months.
• Inventory levels assess how effectively a market absorbs new listings.
• Continuous low inventory levels often mean increased competition and potential capital gains.
• High supply can signify market risks, including depreciation and longer sales periods.
• The inventory metric should be corroborated with other indicators.
• Decreasing inventory often signals a ‘buy’ opportunity.
• Target suburbs with declining inventory below one quarter for optimal results.

The inventory metric is a great place to start to assess the real estate market in a suburb or council area. However, as with all the other supply and demand metrics you should never rely on it in isolation.

Ideally you’d want to target suburbs with decreasing inventory with the current values below 1 quarter (3 months).

However as with all the other supply and demand metrics, inventory levels should not be used in isolation and always cross-checked against indicators such as Stock on Market Percentage, Days on Market, Vacancy Rates and other metrics listed in the HtAG Data Dictionary.

To begin applying the Inventory Metric in real-life scenarios, download the latest suburb report from HtAG Digital Store today.