Odds Calculator

Convert between fractional, decimal, and moneyline odds and calculate implied probability and potential payout.

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Convert between fractional, decimal, and American betting odds and see the implied probability.

Odds format

Enter valid odds Provide odds in the selected format above to see conversions and implied probability.

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Sports & Betting

Convert odds formats and calculate implied probability

An odds calculator converts between fractional, decimal, and moneyline (American) odds formats, and calculates the implied probability and potential payout for any stake. Understanding odds formats is essential for comparing prices across bookmakers and assessing value.

How odds formats relate to each other

Fractional odds like 5/1 mean you win five units for every one unit staked (plus your stake back). The same probability expressed as decimal odds is 6.00, and as American odds is +500. All three express the same payout ratio in different conventions.

Decimal odds are the simplest: multiply your stake by the decimal to get the total return including stake. Fractional odds are traditional in the UK and Ireland. American odds are standard in the US, with positive numbers showing profit on a 100-unit stake and negative numbers showing how much you must stake to win 100.

Implied probability and overround

Implied probability is the break-even win rate implied by the odds. For decimal odds, it is 1 divided by the decimal. For 2.00 odds, the implied probability is 50 percent. Bookmakers set odds so that the total implied probability across all outcomes exceeds 100 percent — the excess is the overround or margin, which is how they profit.

Implied Probability = 1 / Decimal Odds

Multiply by 100 to express as a percentage.

Frequently asked questions

What does "even money" mean?

Even money means the payout equals your stake: you risk one unit to win one unit. In fractional odds it is 1/1 (evens), in decimal it is 2.00, and in American it is +100. The implied probability is 50 percent before the bookmaker margin.

 How do I spot a value bet?

A value bet exists when you believe the true probability of an outcome is higher than the implied probability of the odds offered. If you estimate a team has a 60 percent chance of winning but the odds imply only 50 percent, the bet has positive expected value.

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