What is a market percentage or overround?

The amount by which a betting market's implied probabilities exceed 100 per cent. A market framed to 116 per cent means the prices are collectively 16 per cent worse than fair, and that gap is the bookmaker's margin.

How do you convert odds into implied probability?

Divide 100 by the decimal odds. A $4 chance is implied at 25 per cent; a $2.50 chance is implied at 40 per cent.

What does 'value' actually mean in betting?

A bet has value when the price's implied probability is lower than your own assessed probability of the outcome. It is a long-run concept — any single result tells you nothing about whether the bet was correct.

Where are markets weakest?

In thin midweek markets, in early markets before scratchings settle, and in races where a single piece of information such as a track bias or a gear change has not yet been fully absorbed.

PuntersReview

Racing, read properly.

Market Percentages: The First Number Every Punter Should Learn

What a betting market's percentage actually tells you, and why it's the quickest test of whether a price is fair.

Zac ChristieSports and Racing Analysis14 August 2026

Punters Review editorial artwork

Every betting market adds up to more than 100 per cent. That gap — the market percentage or 'overround' — is the bookmaker's margin, and understanding it is the single fastest upgrade available to a recreational punter.

A market framed to 116 per cent means that, collectively, the prices are 16 per cent worse than fair. Your job is not to beat the horse next to you; it's to find the runners priced at better than their true chance despite that margin.

Converting odds to probability

Divide 100 by the decimal odds and you have the implied probability. A $4 chance is implied at 25 per cent. If your own assessment — or a model's — puts the true chance at 30 per cent, that price represents value regardless of whether the horse wins this particular race.

Value is a long-run concept. Any single result is noise; the discipline is only betting when the implied probability is below your assessed probability, over and over.

Editorial artwork

Where markets are weakest

Markets are sharpest where the most money flows: metropolitan Saturday racing, feature races, short-priced favourites. They are weakest in thin midweek markets, early markets before scratchings settle, and races where a single piece of information — a track bias, a gear change — hasn't been fully absorbed.

Quick answers

What is a market percentage or overround?: The amount by which a betting market's implied probabilities exceed 100 per cent. A market framed to 116 per cent means the prices are collectively 16 per cent worse than fair, and that gap is the bookmaker's margin.
How do you convert odds into implied probability?: Divide 100 by the decimal odds. A $4 chance is implied at 25 per cent; a $2.50 chance is implied at 40 per cent.
What does 'value' actually mean in betting?: A bet has value when the price's implied probability is lower than your own assessed probability of the outcome. It is a long-run concept — any single result tells you nothing about whether the bet was correct.
Where are markets weakest?: In thin midweek markets, in early markets before scratchings settle, and in races where a single piece of information such as a track bias or a gear change has not yet been fully absorbed.

Betting EducationValueMarkets

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