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22 Nov 2023

Understanding sports betting odds and calculating value bets

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Understanding the odds offered on online betting sites is fundamental to placing informed bets, so we created this guide to help you understand their relationship to probability and how to calculate value bets. In addition, we will explore the benefit of having a Skrill account in the world of sports betting.

Sports betting basics

In the context of sports betting, a market is a specific type of bet you can place on a sporting event, for example the outcome of a football match or the number of sets in a tennis match. For each market, there is a betting odd.

Betting odds are numbers that indicate how much you stand to win if you place a bet and the event occurs. In this way, they also reflect the probability that the bookmaker assigns to the event e.g., the likelihood of the visiting team winning.

3 different images with a basketball player, two football players and a tennis player

The higher the odds, the less likely the event will happen. However, as this prediction is never 100% accurate, there is such a thing as a value bet. A value bet occurs when a punter believes that the odds of an event occurring are greater than the odds assigned by the bookmaker, thus presenting potential opportunities.

As odds are an indication of the likelihood of an event or outcome occurring, they are influenced by three factors:

  • The bookmaker’s edge:Online bookmakers include a margin in the odds that ensures their profit. This makes theodds worse than the actual probability of an outcome occurring.
  • Betting volume: If few people are betting on a market, the odds might not accurately reflect the true probability of the event, since bookmakers often adjust them based on the volume of bets they receive. This discrepancy can lead to opportunities for value bets.
  • Reverence: Betting sites may offer lower odds on popular teams or players, as they know that people will bet on them regardless of the odds.

How to interpret betting odds and their probabilities

Betting odds can be presented in different formats, such as decimal odds, fractional odds or money line odds, depending on the region or bookmaker.

1. Decimal odds

Decimal odds represent the total amount you will be paid if the bet wins, including the original stake. To understand the implied probability (probability that the bookmaker believes exists for the event to occur) in decimal odds, the formula is: 1 / Decimal odds Example: 1 / 2.50 = 0.40 (or a 40% chance of the event occurring).

2. Fractional odds

Fractional odds represent the potential profit in relation to the bet. Fractional odds are shown as a fraction, i.e., 3/1 or 5/2. To calculate the odds, the formula is Denominator / (Denominator + Numerator). Example: 2 / (2 + 5) = 0.285 (or 28.5 %).

3. Money Line odds or American odds

Money Line odds, or American odds, have their own way of representing probability. Positive moneyline odds indicate how much you can win with a $100 bet, while negative odds indicate how much you need to bet to win $100. For example, if the American odds are +200, this means that you would win $200 if you bet $100. For positive odds, the formula is: 100 / (Money line odds + 100). For negative odds, the formula is: Money line odds / (Money line odds + 100). If the moneyline odds are -200, the probability of the event occurring would be: 200 / (200 + 100) = 0.67 (or 67%).

Odds comparison table

The table below shows the relationship between the likelihood of an event, the different types of odds and the potential winnings on a $100 bet. Note that increasing the probability of an event reduces the odds and potential winnings.


Money Line   
Winning from a   
$100 bet     
1% 100 99/1 10,000 $10.000
10% 10 9/1 900 $900
20% 5 4/1 400 $400
30% 3.33 2.33/1 233 $233
40% 2.5 3/2 150 $150
50% 2 1/1 100 $100
60% 1.67 2/3 -150 $66.67
70% 1.43 3/7 -300 $47.62
80% 1.25 1/4 -400 $25
90% 1.11 1/9 -900 $11.11
99% 1.01 1/99 -9,900 $1.01


What is a value bet and how to calculate it?

A basketball player scoring a point

A value bet is a bet where you believe that the odds of an event happening are greater than the odds offered by the bookmaker.

The value of a bet is calculated using the formula: Value = (Odds * Odds) - 1. If the resulting value is greater than 0, it is considered a value bet. For example, you would make a value bet when you consider a basketball team to have a 60% chance of winning, but the odds offered imply they have only a 40% chance (approximate decimal odds of 2.50). That is: Value = (0.60 * 2.5) - 1 = 1.50 - 1 = 0.50 (being greater than 0 is value).

The importance of comparing odds

It’s important to compare the odds offered by different sports betting sites, as each has its own algorithm for calculating odds and margin. Comparing odds on a platform such as OddsChecker allows you to identify the betting site offering the best odds.

Failure to compare odds can potentially result in a loss of profit. Paying with Skrill is a great option, as it is accepted at hundreds of bookmakers. So, you can take advantage of great odds whichever bookmaker is offering them.

Person opening the Skrill mobile app

Understanding betting odds is key to more informed sports betting. It helps you to find the best odds and discover value bets.

However, it is important to remember that online betting carries risks and that no system can guarantee consistent winnings. Responsible gambling should always be practiced, limiting yourself to betting only as much money as you can afford to lose.

Using a Skrill wallet allows you to keep your betting balance separate from your bank balance. Skrill also gives you access to private and fast payments at a wide range of bookmakers, helping you to take advantage of the best odds.

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