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    Free tool

    Odds converter

    Decimal, fractional, American and implied chance.

    Odds converter

    Type in any format. The others update.

    %
    Chance of winning40.0%

    Margin / overround

    Enter every price in a market to see the bookie's cut and the fair odds.

    1.90
    1.95
    Overround3.91%
    The bookie's built-in margin.
    #1 fair odds
    1.97
    Margin removed
    #2 fair odds
    2.03
    Margin removed

    How it works

    • Implied chance = 1 ÷ decimal odds.
    • Fractional a/b = 1 + a ÷ b in decimal. American +x = 1 + x ÷ 100; −x = 1 + 100 ÷ x.
    • A market's margin is how far its implied chances add up past 100%.

    Betting involves risk. Bookmakers can restrict or close accounts and void bets, automation can fail, prices move, and a positive expected value (+EV) bet can still lose. Promotions carry each bookmaker's own terms. There is no guarantee of profit. See responsible gambling for limits and support.

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    By the B337 team. Last updated 8 October 2026.

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