Understanding Tennis Betting Odds Formats

Odds are the language of sports betting; they efficiently communicate information to us in terms of betting. In this case, the odds tell us exactly how much money we are being asked to risk and how much we stand to win with any particular bet.

The odds are most often expressed in one of three different formats:

  • Fractional
  • Decimal
  • American

Each of these is popular in different parts of the world, but they all accomplish the same task – which is to express risk vs. reward in sports betting. Most sports betting sites allow you to switch back and forth between different odds formats, so choose the one you like best.

Fractional Odds

Fractional odds display your risk and potential reward using fractions. The number on the left shows how much you stand to win relative to your risk, which is on the right.

For an easy example, odds of 10/1 show that you stand to win ten times your original stake. In this case, a £10 bet would net you £100 in profits.

It is important to note that fractional odds show your net profit. Following the example above, your actual payout would be £110 to account for the return of your original stake.

An even money bet is represented as 1/1 in fractional odds. In that case a £100 bet would pay £100 in net profit.

Whenever you see fractional odds in which the number on the left is bigger than the number on the right, you know you are looking at an underdog. The bookmakers are willing to pay more than your original stake because that outcome is perceived as less likely to occur.

Likewise, you know you are backing a favourite when the number on the right is larger. For example, odds of 1/2 would show that you stand to profit £1 for every £2 risked. A £10 bet at 1/2 would result in a payout of £15 for a net profit of £5.

Examples

Underdogs   Favourites  
Odds Net Profit Odds Net Profit
5/1 £100 nets £500 1/2 £100 nets £50
10/1 £100 nets £1,000 1/5 £100 nets £20
7/2 £100 nets £350 2/5 £100 nets £40
11/4 £100 nets £275 4/9 £100 nets £44.44

 

Fractional Odds Pros and Cons

The advantage of fractional odds is they are easy to understand when the stakes are simple such as 10/1 or 5/1. Even if you’ve never dealt with fractional odds before, you probably already know what people mean when they say the bookmakers “are paying 10 to 1 on so-and-so to win the French Open.”

The disadvantage of fractional odds is they are not as intuitive once we move past simple whole numbers. The more specific an oddsmaker becomes in its pricing model of an event, the stranger the fractions become. That’s when we start seeing prices such as 4/23, 47/20 and so on. It is difficult to visualize that in terms of money risked just by glancing at the price.

Fortunately, online bookmakers provide virtual betting slips that you can use to type in your bet amount and instantly see your potential payout. Even so, it is not as easy to compare different prices using awkward fractions.

Does it take you a moment to determine whether 11/4 or 12/5 pays the most on a winning selection? If so, that’s because fractional odds are not as intuitive. Those same prices in decimal format would be 3.75 and 3.40. You can see that the first price pays the most without even having to think about it when you use decimal odds.

Decimal Odds

Decimal odds do away with some of the complexities of fractional odds by presenting everything to you in nice, clean decimal format. Understanding how much you stand to win is as easy as multiplying your intended bet amount by the odds.

For example, a bet of £100 at odds of 3.50 would return £350.

The key thing to remember with decimal odds is that they show you the total return including the return of your stake. If you’re making the switch from fractional odds, you need to keep this in mind. Fractional odds show your net profit. Decimal odds show your total return.

Because decimal odds include the return of your original stake, 2.0 is an even money bet in decimal format. £100 bet at 2.0 would return a total of £200 for £100 in net profit. 2.0 in decimal format is the same as 1/1 in fractional terms.

Odds lower than 2.0 indicate you are looking at a favourite and will be risking a larger amount than your potential net profit. For example, betting £100 at 1.30 would return a total of £130 for a net profit of £30. A £100 bet at 1.75 would return £175 for a net profit of £75.

Examples

Underdogs   Favourites  
Odds Total Return Odds Total Return
2.50 £100 returns £250 1.80 £100 returns £180
2.75 £100 returns £275 1.36 £100 returns £136.36
3.40 £100 returns £340 1.50 £100 returns £150
8.00 £100 returns £800 1.083 £100 returns £108.33

Advantages of Decimal Odds

The two advantages of decimal odds are they are easy to comprehend (simply multiply your stake by the odds) and they are easy to compare with one another. Whereas it can be a bit confusing to compare different fractional odds to see which pays the most, it is easy to look at two different decimal odds to see which pays the most. The bigger the number, the more it returns.

American Odds

American odds are presented as either a positive or a negative number. Positive numbers show how much you stand to win for every £100 wagered. Negative numbers show how much you must bet in order to win £100.

Betting £100 at odds of +120, for example, would result in a net profit of £120. Positive odds in this case show that you are betting on the underdog. The larger the number, the bigger the underdog and the bigger your potential winnings. Similarly, a £100 bet at +250 would net you £250 in profits.

If instead you were considering a wager at odds of -120, you would need to wager £120 in order to net £100. In this case, you are betting on the favoured outcome. The deeper the numbers are into the negatives, the bigger the favourite. At odds of -600, you would need to risk £600 for a chance at netting £100.

Examples

Underdogs   Favourites  
Odds Net Profit Odds Net Profit
+150 £100 nets £150 -110 £110 nets £100
+200 £100 nets £200 -200 £200 nets £100
+200 £50 nets £100 -200 £50 nets £25
+650 £100 nets £650 -350 £350 nets £100

 

Advantages and Disadvantages

As strange as American odds look to punters from other parts of the world, American odds do have at least one advantage. American odds are better for reflecting minor price movements, say from +120 to +122.

This is easily digestible as you can see at a glance that your potential winnings on a £100 bet have moved from £120 to £122. Trying to show that same price movement in fractional odds would have the odds move from 6/5 to 61/50.

The downside to using American odds is they do not intuitively show your risk vs. reward unless your bet happens to be conveniently sized to work with those particular odds. Calculating how much you stand to win betting £225 at -225 is easy (you would net £100). However, betting £80 at -225 is not nearly as intuitive (you would net £15).

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