Odds calculator

The odds calculator turns decimal odds into an implied probability and works out the return for a stake you choose. It does not predict how likely an event really is. Every result is there to help you understand the numbers in a price.

Convert one price

Enter decimal odds greater than 1 and a stake that is not negative. Both a full stop and a comma work as the decimal mark. At odds of 2.50 and a £10 stake the calculator shows:

• Implied probability: 1 / 2.50 = 40 per cent.
• Return if it wins: £10 × 2.50 = £25, including your stake.
• Profit if it wins: £25 − £10 = £15.

The profit shown only applies if the bet wins. Otherwise the stake would be lost. Taxes, fees, special rules and possible refunds are not included.

Fractional odds

UK bookmakers often show fractional odds. To convert them, divide the two numbers and add 1: 6/4 is 6 ÷ 4 + 1 = 2.50 in decimal, and evens (1/1) is 2.00. The calculator works with the decimal value.

Look at a whole market

The lower part is for all outcomes of the same market that exclude each other and together cover every possibility. In a three-way football market that is home win, draw and away win. For two outcomes, leave the middle field empty.

The calculator adds up the reciprocals of the prices. If the sum is 1.05, for example, the margin over 1 is exactly 5 per cent. The payout rate shown is the reciprocal of that sum. Mixing prices from different markets gives no meaningful comparison.

What are "fair odds"?

Here the margin is spread proportionally across all implied probabilities and taken out. That is a modelling assumption. The calculator does not know the real probabilities, and a bookmaker does not have to spread its margin evenly. The result is therefore no statement about which bet is worth it.

The difference between expected value and an actual payout is explained in What does RTP mean?. For an example with known, equally likely outcomes, try the dice calculator. More tools are in the calculators overview.