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Margin calculator

Enter every price in a complete market from the same bookmaker at the same time. The calculator shows the implied probabilities, the book total and the overround.

Odds format
Market

Enter the details above to see the result.

Returns include the stake; profit is return minus total stake. Nothing is sent anywhere.

What the overround is

Implied probabilities in a fair market would add to 100%. Bookmakers price each outcome a little shorter, so the total is higher; a 105% book carries a 5-point margin. The lower the overround, the closer the prices are to fair.

Fair odds

Dividing each price by the book total scales the market back to 100%. The fair odds shown are the prices the market would show without a margin, not a prediction.

All betting calculators

Pick the calculator for your bet type. Each one follows the same flow: odds format, stake, selections, results.

%Odds converterFractional, decimal, American and implied probability£PayoutSingle bet return and profitΣMarginTwo- and three-way bookmaker marginE/WEach-wayWin and place parts with place termsΣAccumulatorUp to 10 legs4Trixie3 selections, 4 bets7Patent3 selections, 7 bets11Yankee4 selections, 11 bets15Lucky 154 selections, 15 bets26Canadian5 selections, 26 bets÷DutchingSpread a stake across outcomesKKelly criterionStake sizing from your edge⇄HedgingSettle a bet for the same amount either way

Calculators show arithmetic on the numbers you enter. They do not predict results. 18+. BeGambleAware.org.