The Mathematics of Sports Betting: Odds and Probabilities

A detailed look at The Mathematics of Sports Betting: Odds and Probabilities, including in-depth facts.

Imagine that you want to place a wager on the Super Bowl coin toss. This proposition has just two possible outcomes. The coin can either land on heads or it can land on tails. The probability of either outcome is therefore 1/2 or 50%. Now, when you search the internet for “betting sites best odds” and find a reputable bookie, you will likely find that the bookmaker’s odds aren’t exactly in line with those probabilities. 

Instead of the bookie offering even odds on that wager as you might expect, it likely has the odds set at somewhere around 9/10 or 1.90 in decimal form. This is because the bookmakers factor a small commission into their odds. This is how they make money. So, if you stake $100 at 1.90 on the coin flip, you’ll earn a profit of $90 and not $100. Now you need to correctly predict the outcome 52.63% of the time just to break even over the long run. The odds aren’t in your favor.