Enter the bookmaker's odds for a market to reveal their built-in margin (overround). Compare bookmakers and find the fairest odds.
Bookmakers build a profit margin into their odds. If you convert all odds to implied probabilities and add them up, the total will always exceed 100% — the excess is the bookmaker's margin (also called the overround or vig).
Example: Home at 2.10 (47.6%), Draw at 3.40 (29.4%), Away at 3.50 (28.6%) = total 105.6%, so the margin is 5.6%.
Lower margins mean better value for you. Top bookmakers like Pinnacle offer 2-3% margins, while average bookmakers charge 5-8%.
The bookmaker margin (also called the overround, vig, or juice) is the built-in profit that every bookmaker takes on every market they offer. In a perfectly fair market, the implied probabilities of all outcomes would add up to exactly 100%. In practice, bookmakers set their odds so the total is always above 100% — and the difference is their guaranteed profit regardless of the result.
For example, a fair coin flip has 50/50 odds (2.00 on each side). But a bookmaker might offer 1.91 on both heads and tails — implying 52.4% on each side, for a total of 104.8%. That 4.8% is the margin. For a deeper explanation, read our article on bookmaker margin and why it matters.
The margin directly affects your bottom line. A bookmaker with a 2% margin gives you odds much closer to the true probability than one with an 8% margin. Over hundreds of bets, this difference is substantial. Betting at lower margins is one of the simplest ways to improve your long-term results without changing anything about your selection process.
Use this calculator to compare margins across bookmakers for the same match. If Bookmaker A offers a 3% margin and Bookmaker B offers 7%, you are losing twice as much to the house with B — even if the headline odds look similar.
Not all margins are equal. Here is how to interpret what the calculator shows you:
This calculator also shows the fair odds — what the odds would be if the bookmaker charged no margin at all. Comparing fair odds to the actual bookmaker odds tells you exactly how much value is being taken from each outcome.
If the fair odds for a home win are 2.20 but the bookmaker offers 2.05, you know that outcome is carrying more of the margin burden. Savvy bettors use this information alongside the EV Calculator to find bets where the bookmaker has priced an outcome too generously relative to its true probability.