Formula Journal
What Is a Good Days on Market Number? — DOM Thresholds That Actually Mean Something
Days on market gets mentioned in every property report, every buyer’s agent briefing, every suburb wrap-up. But almost nobody defines what “good” actually means. Is 30 days fast? Is 60 days too slow? Does it depend on the city?
The short answer is: DOM is one of the clearest real-time tightness signals in property — but only when you know what thresholds to use and why. Here’s what we learned building a backtested suburb-scoring formula that uses DOM as a hard filter and a weighted component.
What DOM Actually Measures
Days on market is the median number of days a property sits on the market from first listing to sale. It’s a direct read on the balance between buyer demand and seller supply in a specific suburb.
When DOM is low, it means properties are being absorbed by buyers quickly. Sellers have the upper hand — they don’t need to discount, they don’t need to wait. When DOM is high, supply is outpacing demand. Buyers can take their time, negotiate hard, and often pick up a discount.
What makes DOM useful is that it’s a lagging indicator in the best possible sense: it confirms something that’s already happening in the market rather than speculating about something that might happen. If DOM is falling, buyers are getting more competitive. If DOM is rising, the market is cooling. It’s the pulse rate of a suburb.
Why this matters
DOM doesn’t tell you whether a suburb will boom. It tells you whether demand is currently outstripping supply. That’s a component of a detection signal — not a prediction signal. The distinction matters, because prediction doesn’t work at suburb level with publicly available data.
What Different DOM Ranges Mean
There’s no single “correct” DOM number for Australia as a whole — a 45-day DOM in Perth means something different to 45 days in inner Sydney. But the direction and extremesare interpretable anywhere. Here’s how to read the ranges.
Properties are being sold almost before buyers can arrange inspections. This is a seller's market in the strongest sense — multiple offers, minimal negotiation, often above asking price. If you see DOM under 20 in a suburb that also has growth above 5% and vacancy under 2%, that's a boom signature.
Healthy absorption. Sellers aren't struggling, but buyers still have a realistic shot at a fair process. This is the range where BoomAU's hard filter kicks in — 45 days is the upper bound for a suburb to qualify for scoring at all. Below this line, the market is moving fast enough to register demand pressure.
Around the long-run national average for many markets. Sellers need to be realistic on price. Buyers have negotiating room. A suburb in this range isn't booming — it's treading water. Not a red flag on its own, but not a tightness signal either.
Properties are sitting. Either asking prices are too high, demand has softened, or supply is flooding in. Buyer discounts become normal. If DOM has been in this range for 12+ months, the suburb is in a genuine slowdown — not a buying opportunity in the near term.
At this point, many listings are either overpriced, in markets with structural demand problems, or both. This is also the range where missing or sparse data starts to distort suburb-level statistics — a suburb with only 8 annual sales will show erratic DOM figures.
BoomAU tracks DOM for 393 suburbs, fortnightly
Only suburbs with DOM under 45 days qualify for scoring. Join the wishlist to see which suburbs are passing the filter right now.
Why We Use 45 Days as the Hard Filter
BoomAU’s formula v2.3 uses four hard filters. A suburb must pass all fourto be scored at all — regardless of how strong its other signals are. DOM is one of them.
Hard filters — all must pass
- •Growth >= 5% annually
- •DOM <= 45 days
- •Vacancy rate <= 2%
- •Median price <= $800K
The 45-day threshold wasn’t chosen arbitrarily. In the 78-suburb backtest, every suburb that genuinely boomed had DOM well below 45 days during its boom period. Suburbs with DOM above 45 consistently showed no boom behaviour — regardless of their growth rate or vacancy rate.
The filter is binary: either the market is absorbing supply fast enough to register genuine demand pressure, or it isn’t. A suburb with 60-day DOM and 8% annual growth is not booming — it’s probably just expensive, with a small number of high-value transactions inflating the median. Filtering it out prevents false positives.
Zero false positives on 78 suburbs tested. The 45-day DOM filter was part of why. Every suburb the formula flagged as a boom was genuinely booming. The 20.2-point separation gap between real booms and false signals means it’s not close calls — the formula gets it with conviction.
Takeaway
DOM above 45 days is not a nuance to weight — it’s a disqualifier. If you’re evaluating a suburb for near-term growth potential and DOM is above 45, the market is telling you something. Don’t override it with a compelling story about infrastructure or population.
DOM as a Tightness Score, Not Just a Filter
Passing the 45-day hard filter is the floor. For suburbs that clear it, DOM becomes an ingredient in the formula’s Tightness component — one of five weighted inputs.
| Component | Weight | What it measures |
|---|---|---|
| Momentum | 0.30 | Price growth acceleration |
| Growth Strength | 0.25 | Annual growth scored directly |
| Tightness | 0.20 | DOM + vacancy rate ← DOM lives here |
| Sustainability | 0.15 | Rental yield + vacancy trend |
| Headroom | 0.10 | Price relative to capital city median |
Tightness carries 20% of the total score. Within that component, DOM and vacancy rate combine to measure how constrained supply is relative to demand. A suburb with 15-day DOM and 0.8% vacancy will score near the top of the Tightness component. A suburb with 44-day DOM and 1.9% vacancy will score near the bottom — and still pass the hard filter, but with very little tightness contribution.
This design is intentional. DOM and vacancy measure the same thingfrom different angles — how fast existing listings are absorbed (DOM) and how much rental stock is sitting unoccupied (vacancy). Combining them reduces noise from thin markets where one metric might be missing or erratic.
Which brings up the nastiest failure mode in DOM-based scoring.
Why a Suburb’s DOM Number Can Lie to You
A DOM figure is a median. Medians need volume to behave. In a suburb that sells 200 houses a year, a median days-on-market of 38 is a real description of the market — dozens of transactions sit on either side of it. In a suburb that sells 12 houses a year, the same 38 is barely a statistic at all. It’s the midpoint of a tiny sample that could swing thirty days in either direction depending on which single listing closed next.
This is what makes thin-market DOM dangerous. One well-priced home sold to a motivated buyer can pull the median to 10 days and make the suburb look white-hot. One tired listing that drags for six months can push it to 150 and make the same suburb look like it’s stalled. Neither number is wrong. Neither is useful. At low volumes, DOM stops being a signal and starts being the echo of whichever handful of properties happened to transact.
The cleanest example: regional and fringe suburbs routinely appear at the top of DOM rankings with numbers that look incredible — 8 days, 12 days, 15 days — only to reveal on closer inspection that they sold fewer than twenty homes across the entire year. A couple of fast sales, an otherwise sleepy market, and the median lands somewhere that flatters the suburb into a ranking it hasn’t earned.
Practical rule: always check DOM against sales volume
Treat DOM with scepticism in any suburb selling fewer than ~30 properties a year. Below ~15 annual sales, the DOM figure is not usable at all — the sample is too small for a median to mean anything. Before you trust a DOM number, check how many homes actually changed hands behind it.
We handle the data gaps so you don’t have to
DOM tracking for 393 qualified suburbs, fortnightly updates, with data validation built in. Join the wishlist.
How to Use DOM in Your Own Research
You don’t need BoomAU to get DOM data. The information is publicly available — the challenge is interpreting it correctly and tracking it at scale. Here’s how to read it when you’re evaluating a suburb.
1. Check the absolute number against the 45-day threshold
If DOM is above 45 days, the suburb fails the most basic tightness test. Don’t try to rationalise it with other metrics. Move on and find a suburb where the market is actually moving. Below 45 is the floor for genuine demand pressure.
2. Look at the trend, not just the snapshot
A suburb with 40-day DOM today that was at 70 days twelve months ago is in a fundamentally different position to one that’s been at 40 days for three years. Falling DOM is the early tightening signal. Rising DOM is the early cooling signal. The direction matters as much as the level.
3. Cross-check with vacancy rate
DOM and vacancy measure demand pressure from different angles. If DOM is low but vacancy is above 2%, that’s a mixed signal — the for-sale market is tight but the rental market has slack. True tightness shows up in both. SQM Research publishes free postcode-level vacancy data going back 16 years.
4. Be sceptical of thin market figures
If a suburb sells fewer than 30 properties a year, the median DOM figure is going to jump around. A single outlier — a property that took months to sell at an unrealistic price — can distort the whole suburb’s number. Check volume alongside DOM. Below about 20 annual sales, the data gets noisy enough to be unreliable.
What DOM Can’t Tell You
DOM is a powerful tightness signal. It’s not a complete picture. There are two things DOM cannot do, and misusing it for either is expensive.
It can’t tell you whether a suburb will outperform others. When we tried to use DOM as part of a cross-suburb ranking model — one that predicts which suburbs will outperform others after cancelling the market tide — it failed. So did acceleration ratio, 5-year momentum, and virtually every metric investors obsess over. The only cross-suburb ranking signal that survived backtesting was affordability headroom: how a suburb’s median price compares to its capital city median.
It can’t tell you whether a boom will start. DOM is a detection component, not a prediction component. A suburb with tight DOM today may have been tight for two years with zero price movement. Tightness is a necessary condition for a boom, not a sufficient one. That’s why the formula requires five components to align simultaneously — Momentum, Growth Strength, Tightness, Sustainability, and Headroom — before a suburb registers above the boom threshold of 80.
The detection timing reality
BoomAU’s formula catches booms 6–12 months after they start. That might sound late. But booms are multi-year events — detecting one in its early phase still captures 60–85% of total gains, with far higher confidence than trying to pick the very start. DOM tightening is often one of the first signals a boom has begun, which is exactly why it sits inside the detection formula rather than a prediction one.
What Good DOM Tracking Gets You in Practice
When you combine DOM with the other four components of a detection formula and run it at scale, the tier discrimination results are striking.
| Tier | Excess return | Beat market | n |
|---|---|---|---|
| Strong | +7.5pp | 71% | 2,103 |
| Good | +1.3pp | 55% | 3,349 |
| Fair | −0.7pp | 47% | 5,788 |
| Weak | −6.4pp | 28% | 1,120 |
Walk-forward backtest, 12,360 postcode-months. Excess return = suburb 12-month growth minus market median growth. Full methodology →
Perfectly monotonic. Strong Signal suburbs outperform by +7.5 percentage points on average. Weak Signal suburbs underperform by 6.4pp. The 13.9pp spread between the best and worst tiers is the gap that suburb-level DOM tracking — combined with the other formula components — helps you navigate.
A suburb with DOM above 45 days won’t appear in Strong or Good Signal. It can’t — it fails the hard filter. That exclusion is the formula working as designed.
DOM tracked fortnightly across 393 scored suburbs
BoomAU applies the 45-day filter automatically. Join the wishlist to see which suburbs are clearing it.
The Practical Summary
If you want to use DOM in your own suburb research without a scoring formula, here’s the condensed version of what backtesting validated:
Use 45 days as your floor. If DOM is above that, the suburb isn’t showing demand pressure. Don’t let other metrics override it.
Watch the direction. Falling DOM over 6–12 months is more informative than a single snapshot. That’s tightening happening in real time.
Always pair it with vacancy rate. Low DOM plus low vacancy (under 2%) is the tightness signature that survived backtesting. One without the other is a weaker signal.
Check annual sales volume. DOM from 15 or fewer annual sales is statistically unreliable. Thin markets can show extreme DOM figures that mean nothing.
Remember what it can’t do. DOM alone won’t tell you which booming suburb will outperform. For that, the only signal that survived backtesting is affordability headroom — price relative to the capital city median.
Full backtest methodology, the 78-suburb validation, and the walk-forward tier discrimination results are published on our proof page. No gating, no email required. Check the numbers yourself.
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