Betting odds explained

Andy Schooler

29 November 2022

Betting odds represent the perceived chance of something happening and consequently determine how much a punter can win or lose. 

The chance of an outcome happening is considered low if the fractional or decimal odds are high, and vice versa.

Fractional and Decimal Odds

Fractional odds, such as 9/2 or 10/1, have traditionally been most associated with betting. However, like most other exchange betting platforms, Smarkets uses decimal odds as its default setting.

With decimal odds, the figure represents the return on a bet of £1. Therefore, if you win a bet at odds of 5.5, you get £5.50 back for every £1 you wager. Note that the original stake is included in this figure, so the profit on the bet is £4.50.

If the decimal odds figure is less than 2 (E.G 1.4), then that outcome is considered more likely to happen than not. If this is the case, you may hear that outcome described as ‘odds-on’. An example that you might hear often is that Manchester City are odds-on to win a football match.

American and Percentage Odds

Other odds formats also exist, and we understand some of our customers would prefer to use these. Customers can change their settings so that odds show in the American format, or by percentage.

The American format uses numbers related to stakes or winnings of £100.

If the odds are a positive figure (E.G +200), they show how much profit you could make by placing a £100 bet. So, in this example, you would make £200 profit for every £100 placed.

If the odds are a negative figure (E.G -150), they show how much you need to stake to win £100. So, in this example, you would need to bet £150 to win £100.

As for percentage odds, these show the perceived chance of something happening in percentage terms. The table below shows some commonly-used odds in their various formats.

Fractional Decimal American Percentage
1/2 1.5 -200 67%
4/5 1.8 -125 56%
1/1 2 +100 50%
6/4 2.5 +150 40%
13/8 2.63 +163 38%
2/1 3 +200 33%
7/2 4.5 +350 22%
5/1 6 +500 17%
10/1 11 +1000 9%
100/1 101 +10000 1%

Andy Schooler

29 November 2022

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