Each-Way AtlasEach-way betting explained
Are bookmaker odds fair, or does the margin rule out long-run wins?
Partly true: the margin is real and measurable, yet the arithmetic cannot show that long-run wins are almost impossible. The claim, made in a reader's question, is that the margin rules out winning over time. In an invented five-runner market the implied probabilities total 104.4%, returning 95.7p per £1 if the fair shares hold.
Editorial team of Each-Way Atlas · Checked
The claim we checked
A reader asked whether bookmaker odds are fair or whether the margin makes winning in the long run almost impossible. We split it into two parts: whether a margin exists, and whether it rules out long-run wins.
The short version: the first part can be calculated, and the second part cannot.
Facts: the margin in an invented market
The margin, or overround, is the amount by which the implied probabilities of all runners exceed 100%. Each probability is 1 divided by the decimal price. See implied probability.
| Runner | Decimal price | Implied probability | Fair share after removing margin |
|---|---|---|---|
| A | 2.50 | 40.0% | 38.3% |
| B | 3.50 | 28.6% | 27.4% |
| C | 5.00 | 20.0% | 19.1% |
| D | 9.00 | 11.1% | 10.6% |
| E | 21.00 | 4.8% | 4.6% |
| Total | 104.4% | 100.0% |
The short version: the five prices imply 104.4%, so the margin in this invented market is 4.4 percentage points.
What does the margin mean for a bet?
If the fair shares in the table were the true chances, £1 spread across the field would return 1 ÷ 1.044 = £0.957 on average, so 4.3p per £1 would go to the margin. That is a statement about prices, not about any real race.
The place part has its own margin. Fair place chances add up to the number of paying places, and the quoted place prices add up to more than that.
The short version: a margin lowers the average return per £1 unless you hold better information than the price.
What can and cannot be checked?
- Checked: the arithmetic of the table, which you can repeat with a calculator.
- Not checked: that real races have these true chances, because we hold no frequency data.
- Not checked: any claim about long-run results of a bettor, because that depends on the bettor's staking and information.
- Not verified: a regulator's definition of margin, which we will add with a source and date.
The short version: the margin is a cost you can calculate, and the long-run outcome is not something this page can prove.
Why does this matter for your safety?
A margin means that betting costs money on average, so only stake what you can afford to lose and set limits. Read the support material from GambleAware and the GamCare support page.
National Gambling Helpline 0808 8020 133 is free and open 24 hours a day. See our page on responsible gambling.
The short version: treat betting as a cost, set limits, and use the free help if it stops being a game.
How we checked
On 7 November 2026 we worked the example by hand and listed the sources still to be recorded: a margin definition and the support pages above. The related fact check is do reduced place terms make each way a losing bet. See how we check.
18+ only. Gambling can be harmful.
The short version: the calculation is checked and the definition source is still to be added.
What changed
7 November 2026: first version, with an invented market. Return to the each-way hub.
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