The odds quoted on an online sports bet tell you how much your stake will earn if you win. They are also an indication of the probability of that win; short odds, in which bets pay out even money or less, tell you that this option is the favourite, expected to win.
If you stand to win a hundred times your stake instead, you are looking at long odds with a tiny chance of winning. What can confuse newcomers to online sports betting is the way in which odds are phrased. There are three systems, and you will find them at different betting sites according to their local traditions.
Also called “British”, “UK” or “traditional” odds, fractional odds use two numbers separated by a slash, a dash or a colon. The odds 10/1, 10-1 and 10:1 are all pronounced “ten to one”. If this bet wins, the punter is paid 10X the stake, and of course the stake is returned. The total paid to the player is thus 11X the stake.
Odds of, say, 5/2 mean that for every $2 wagered, the player is paid out $5; a $20 bet could win $50, for a total return of $70. Favourites quoted at these odds often have a larger second number; for example, 1/5 odds will only return $2 profit on a $10 bet, for $12 in total.
Decimal odds, or “digital” or “European” odds, express the total return on a winning bet, including the returned stake, as a decimal fraction. Decimal odds of 1.5 mean that the punter stands to win half the stake: fractional odds of 1/2.
Because they must include the stake, decimal odds can never be less than 1.0, although the closer they get to that number, the more you know you are backing a favourite. They can get much bigger than 1.0, of course: decimal odds of 101.0 are equal to fractional odds of 100/1
Moneyline Odds From The US
Moneyline odds are also called “American” or “US” odds, once again based on their place of origin. This system expresses odds as a positive or negative number. It’s easiest to explain with examples.
Imagine two teams meeting in a match, named Tops and Bottoms. Bottoms haven’t won a match all season and are being plagued by injuries. The bookmaker offers them at +1000. To work out the return, divide the positive figure by 100, and the answer is 10. The odds are 10/1, or 11.0 in decimal notation; a punter betting $100 receives a total of $1100 if they win.
Tops haven’t lost a game all season, and they’ve already beaten Bottoms in an away match. They are the favourites, so they are offered at -250. To work out this return, divide 100 by the negative number, 250. The answer is 0.4; then multiply it by the stake. A $100 bet can therefore win $40, for a total return of $140, odds of 2/5 as a fraction or 1.4 in decimal.
As a benchmark, remember that odds paying even money can be expressed as 1/1, 2.0, or +/-100.