Home Sports The Layman’s Guide To Understanding How Betting Odds Are Calculated

The Layman’s Guide To Understanding How Betting Odds Are Calculated

The Layman’s Guide To Understanding How Betting Odds Are Calculated

Top tips for understanding betting odds: How understanding the odds can help you

For many people looking at betting odds can be confusing, but it is essential to understand what you are talking about before you place a bet. From margins to probability and even how these things are phrased in other countries, understanding the odds is crucial when making up your mind and here we have a few tips to simplify it for you.

What are the odds?

Firstly, we need to know what odds are. Basically, betting odds are put together by Bookmakers to tell you how likely something is to happen. For example, if you want to understand how tennis bet odds work, you will first need to check to see what the tips are about each player and what their chances are. There are odds on all sorts of things happening, from the obvious sporting events to who the next Bond will be and even the next President or Prime Minister. These likelihoods are usually written as a fraction, like 4/1, though different countries can use their own systems.


To understand betting odds, you have to know what probability is. This is the likelihood of something happening, like rolling a specific number on a normal die or getting heads on a coin when you flip it. You know what these probabilities are, and they are written like 1/1 for a coin toss, a 50:50 chance at heads or tails each time you throw it.

Putting them together

Now you have your odds you can use it to calculate the probability that something will happen. Take your number, say 4/1. You take the bottom number, 1, and put it over the other number which you will add the one to get the likelihood of it happening. Confused? Look at it like this:

4/1 = 1/ (4+1) or 1/5 which equals 0.20, a 20% or 1 in 5 chance this will happen. Here are a few more examples for you to get your head around:

  • 100/1 = 1/101 or less than a 1% chance
  • 20/1 = 1/21 or less than 5%
  • 3/2 = 2/5 or 40%

Still with me? Now you have to put it into practice.

Betting Odds

Once you can work out your probability and see how likely something is to happen, you will also see how much money you would get back if you win. A 10/1 bet pays out 10 for every 1 bet, plus the original stake of 1 so 11! Simple, right? Numbers that are bigger after the / are more likely than not to happen as considered by the bookie, and so you have to risk more for a smaller pay out, while the opposite is true of a bigger number coming first.

Other systems

Decimals are another popular way to show betting odds in Europe, where the stake is included so as to keep it simple. An 11.0 bet would be a win of 10 with the 1 stake included and so on. In the US they use a different system instead of fractions or decimals, using + or – to show who the favourite is and who you would have to bet more on to get less back.

There are many systems and details when it comes to betting odds, but remember to think about the likelihood of something happening, factor in the stake and know it is not as confusing as it seems!