Decimal odds in plain English
Decimal odds show the total return, including your stake. A €10 winning bet at 2.50 returns €25: €15 profit plus the €10 stake. The implied probability is 1 divided by the odds. Odds of 2.00 imply 50%; 1.50 implies 66.67%.
Calculate the bookmaker margin
Add the implied probabilities for every mutually exclusive outcome. If two tennis players are priced at 1.80 and 2.10, the total is about 103.17%. The amount above 100%—about 3.17 percentage points—is the market overround. It is a comparison tool, not the bookmaker’s guaranteed profit on one event.
Compare like with like
Prices change continuously. Compare the same event, market rules, selection and timestamp. Check whether overtime counts, whether a draw is a third outcome and whether the bet is void after a venue change. A superficially larger price can come with different settlement rules.
Price is only one factor
A low margin is useful only if the bookmaker is locally authorised, accepts the bet fairly and pays valid withdrawals. Consider market depth, limits, settlement history and account restrictions alongside price. Never increase stakes simply because an offer is described as value.
Practical checklist
- Use the official regulator or source, not a copied badge.
- Save the relevant terms and date before depositing.
- Check the exact domain, legal entity and country rules.
- Set money and time limits before you start.