Understanding Betting Odds

Betting odds help punters understand their potential winnings and the probability of a particular outcome. The most popular betting system is fixed-odds betting, where the bookmaker offers the odds before the event. The different types of odds used in the fixed-odds betting system may be confusing, but the experts at Slotegrator have prepared a comparison and explanation.

1. Fractional odds

Fractional odds, mainly used in the U.K. and Ireland, are quite popular in horse racing. They are usually displayed as 10/1, 7/2, 4/1, etc. Let’s look at the examples of how these odds are calculated.

The easiest way to understand fractional odds is to think of the first number as “how much you will win,” and the second one as ”how much you bet”:

  • if you bet £1 at 10/1, you will win £10 + get £1 back;
  • if you bet £2 at 7/2, you will win £7 + get £2 back;
  • if you bet £1 at 9/1, you will win £9 and get £1 back.


1/1 = A/B

((Bet/B) x A) + Bet

There is also the possibility that odds will be displayed the other way round - for example, 1/10, 2/7, 1/4. In this case, punters will have to bet £10 to win £1. These odds usually appear when there is a strong favorite to win:

  • if you bet £4 at 1/4, you will win £1 + get £4 back.

Then, there are fractional odds that are called evens:

  • if you bet £1 at 1/1, you will win £1 + get £1 back.

Fractional odds are typically represented with a "/" but can also be represented with a "-".

Do not miss: Guide to Betting Feeds and Stats

Fractional odds help to calculate how likely a given event is to happen (the probability that a team or horse will win). The calculation is: Probability (%) = B / (A+B).

  • 9/1 for a team: 1 / (9 + 1) = 0.10. There is a 10% chance the team will win.
  • 1/4 for a horse: 4 / (4 + 1) = 0.80. There is an 80% chance the horse will win.

Do not miss: Risk Management in Sportsbooks

2. Decimal odds

Decimal odds are mainly used in Europe, Australia, Canada and most of the rest of the world. Decimals are considered easier to understand than fractions, and they are written as 1.80 or 9.0.


(Odds x Bet) - Bet
  • if you bet £10 at 9.0, you will win £80 + get £10 back;
  • if you bet £10 at 4.0, you will win £30 + get £10 back;
  • If you bet £10 at 1.25, you will win £2.50 + get £10 back.

To calculate the final winnings including the original bet, it is easiest to use the formula (Odds x Bet).

Even decimal odds are displayed as 2.0.

3. Moneyline odds

Moneyline odds are used primarily in the USA. They are usually presented as +100, -400, etc. Positive odds are used for an outcome that is considered less likely to happen, while negative odds are used for favorites.


Positive odds indicate how much money will be won on a $100 bet.

Negative odds indicate how much money must be bet to win $100.

  • if you bet $100 at +400, you will win $400 + get $100 back.
  • if you bet $160 at -160, you will win $100 + get $160 back.

In this case, even odds are displayed as +100 or −100.

Betting odds may be confusing at first, but they are useful for calculating potential winnings and understanding the probability of the event’s outcome, which help punters decide what team to back at the event.

Leave a comment

By clicking this button, you agree to our Terms of Service and Privacy Policy.
Never miss any iGaming updates
By clicking this button, you agree to our Terms of Service and Privacy Policy.


Your message has been successfully sent

By continuing to browse or clicking on the accept button, you accept our website's cookies policy. Find out more.