Understanding Sports Betting Odds

When you first decide to place a sports bet, you might head to the page only to be confronted by the different odds. These can be one of the most confusing parts of trying to master a sports betting site and its offers, but it is something that you need to make sure you understand.

Luckily, these only appear to be difficult to understand! Once you know the trick of how to interpret them, things should be quite simple for you to work out. There are three main formats and you will probably find that you gravitate more towards one of them over the others. Let’s take a closer look at these formats and how you can use them to work out the implied probability of an outcome.


Sharon McFarlane
May 24 2021

What are the types of odds?

You will always find odds expressed in either the American, decimal or fractional formats. Though a sports betting site might choose one of these as a default, you will often be able to change the display to your preferred format.

No matter the format, they will show the implied probability of the outcome of whatever bet they are attached to, and they will show how much you can expect to win on that bet.

American Odds

American odds are easily identified as they are expressed by three digits, with a +/- in front of them. These will show your payout, but they will also show the underdog and the likely winner for the chosen sports event. Any negative number indicates how much you would have to bet to win back $100 if you were to bet on the favourite. The positive is the same, but for the underdog of a match.

Let’s take an example here using the NFL. You want to bet on an American football match between the Seattle Seahawks and the San Francisco 49ers. The Seahawks have odds of +150 and the 49ers have odds of -120, thus indicating that the 49ers are the favourites to win the game.

The formulas for calculating these odds tend to vary a little depending on whether you are betting on the favourite or the underdog:

Favourite Underdog

Win = (100 x Bet)/Odds



Win = (Bet x Odds)/100

If you were to place a £10 bet on the Seahawks and they won, you would win (10×150)/100, a win of £15 and a total win of £25.

A winning bet on the 49ers meanwhile, using that same £10 wager, would grant a win of (100×10)/120, or £8.33, so you would have a total win of £18.33.

Want another example? Let’s take an example from the English Premier League, with a hypothetical match between Chelsea and Newcastle. Chelsea has odds of -225, and Newcastle has ones of +550. This shows that Chelsea is the favourite to win.

If you were to put a winning of bet of £15 on Chelsea, your formula would look like (100 x 15)/225, giving you a win of £6.67, for a total win of £21.67.

Meanwhile, a winning bet of £15 on Newcastle would give you a formula that looks like (15 x 550)/100. This gives a win of £82.50 and a total win of £97.50. A bet of Newcastle here is going to pay out a lot more simply because Chelsea are the clear favourites to win. Though there is always the chance that Newcastle will pull out a win, they are very much the underdogs for this game.

Decimal Odds

Decimal odds are some of the most straightforward to work with. If you are searching for an easy layout and interpretation of odds, this should be the one you go for.

The formula for calculating your winnings is incredibly easy to use:

Win = (Bet x Decimal Odds) – Bet

Let’s put this into practice with an example based in the English Premier League. Tottenham Hotspur has odds of 3.50 to win, while Manchester City has odds of 2.00.

If we were to bet £20 on Tottenham, we would stick this into the formula to get (20 x 3.5) – 20. This would give winnings of £50.

Meanwhile, with Man City, the formula would read as (20 x 2.00) – 20. The winnings would therefore be £20.

Need another example? Let’s take a look at a rugby union match between England and France. England has odds of 1.85 to win, while the bookie has given France odds of 1.93.

So, if we bet £25 on England, our formula would read as (25 x 1.85) – 25, with a resulting win of £21.25.

Meanwhile, our formula for a £25 bet on France would be (25 x 1.93) – 25. This would give a win of £23.25.

Fractional Odds

Finally, fractional odds are the ones most used in the UK. If you are looking to place a bet at a UK sports betting site, it is likely that the odds will be expressed in the fractional format by default. They can be a little confusing to manage, but when you know the tricks, they can be fairly straightforward.

The formula for calculating the return on a fractional stake is:

Total Payout = (Bet x Fractional Odds) + Bet

As you can see, this is quite similar to the way decimal odds are calculated, but this method will give you your total payout and not just your winnings.

Of course, this is always best explained with an example! Let’s imagine that Roger Federer is in the Wimbledon final, and your favourite bookie has given him odds of winning at 7/1. If you place a £50 bet on him, your return formula will look like (50 x 7/1) + 50, giving a total payout of £400!

As always, let’s take another example just to further explain things. Let’s say that the LA Clippers in the NBA have odds of 10/11 on them for a game. If you were to place a bet of £30 on them, this would give a formula of (30 x 10/11) + 30. This would give you a total win of £57.27!

Which Odds are Best for You?

Ultimately, you just need to take a look at the various odds and decide which one works best for you. The way in which the bets are expressed will depend a lot on the site that you choose to bet at and where you are looking for tips.

For example, if you are invested in the NFL and want to follow how certain teams are predicted to perform, you should probably get to grips with American odds. Any tips sites or American sportsbooks that you look at are going to display their odds in this way. While the sportsbooks might allow you to convert the odds to a different format, the tips sites won’t so you may have to find a conversion calculator if you can’t read American odds.

Likewise, if you want to follow British or Irish horse racing, these odds are usually expressed using the fractional layout. Fractional odds are also just more popular in Britain and Ireland in general. Even if you have your favoured online betting site set to decimal odds for when you place your bets, knowing how fractional odds can be read will help you work out bets on the go – so if you see odds that catch your eye, you are able to work out their potential payouts in a flash.

Those who are new to the world of online sports betting should definitely try to get to grips with decimal odds first, as these are the most straightforward, but don’t neglect American or fractional odds.

Here at PlayRight, we are always searching for great online sports betting sites that offer fair odds, no matter how they are expressed! Take a look at some of our favourite UK online bookies now!

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Written by: Sharon McFarlane
May 24 2021
creating content within the iGaming sector for over 11 years. Throughout that time she has worked with blue-chip operators and affiliates to create objective and unbiased copy that would add value to the user