Overround explained: How it impacts your potential winnings
It’s common knowledge that sports betting is a game of numbers and probabilities. However, most people don’t pay attention to where the numbers come from, simply focusing on the fact that lower odds mean a higher probability.
If you are not aware, behind every set of odds is a hidden margin that bookmakers add to ensure they make a profit regardless of the outcome. This is called the overround, and it’s one of the most important numbers you need to understand before focusing on online sports betting and odds in Ireland or anywhere.
What is overround?
Overround, often referred to as the bookmaker’s margin or vig (short for vigorish), is an extra percentage added by the bookmarker to take the implied probability percentage beyond 100%.
In an ideal world, the total probability of a team winning or losing would be 100%, like in a coin toss. However, if half of the betters place their bets on Team A and the rest on Team B, the bookmakers would give out all winnings despite taking the risk and providing the platform.
To ensure they make a profit in such a scenario, they take the implied probability of the events beyond 100%. For example, in an event with two outcomes, you might see outcome A with a probability of 52% and 51% for outcome B. This adds up to 103%, with the extra 3% being the overround.
How overround is calculated
While it may sound complicated, calculating the overround is quite simple. It only involves converting the given odds to the probability percentage and then subtracting 100%.
For example, in a football match, you might get these odds:
- Team A: 2.5
- Team B: 2.5
- Draw: 3.0
To get the percentages, convert the odds by dividing them by 100. 2.5 will give you 40%, while 3.0 will give you 33.33%.
This means that the implied probability of the outcomes is 40%+40%+33.33%, giving you 113.33%. When you subtract 100%, you get 13.33%. This is the overround, or simply, vig.
How it impacts your potential winnings
The overround isn’t just a technical detail of gambling mathematics but a key number that also affects your potential winnings. It’s a margin like any other used in retail, so a bigger one means that your take-home is less.
For example, if you place a bet on odds with an overround of 10%, the bookmaker will keep more of your money compared to if you place the same bet on an overround of 5%. The difference might seem small in one bet, but it accumulates to a significant amount over time.
This means that before you place a bet (especially when wagering big amounts), it’s good to calculate the vig and compare it with other bookmakers.
How to minimize overround’s impact
Overround is inevitable as all bookmakers need to earn from their platforms. However, there are some strategies you can use to minimize its effect on your winnings.
Shop Around for Better Odds
The easiest way to deal with overround is by shopping around. While bookmakers will have similar probabilities for an event, the overround can vary significantly from one to the other. This is what results in “better odds” when you compare different bookies. If you find one whose percentage is consistently close to 100%, stick there.
Focus on Popular Markets
High-profile events like major football matches or tennis tournaments often have less overround. This is because sportsbooks try to outdo their competition in popular events, resulting in better odds.
Focus on More Efficient Markets
Sportsbooks today offer a wide range of markets, from whether a player scores to the number of corners in a football match. However, these niche markets are unpopular and quite risky for the bookmaker, so they tend to have huge percentages of overround.
To increase your winnings, it’s advisable to focus on major markets like match outcomes, goals scored, and handicaps. Since they are popular, they are also more competitive. However, that doesn’t mean you can’t try out prop bets, as they are actually quite fun. Just remember to gamble responsibly.
