Overround Calculator

Overround, also known as the book percentage, is the combined total of priced probability across all outcomes on a single event. The price of each event in a given market directly correlates to the percentage chance of that event winning. The overround adds all these percentages to give the bettor an idea of the formulation of the market. In a perfect world, these totals would add up to 100%, however in order for bookmakers to make profit on markets, it is not uncommon to see markets in the range of 120% - to 130%, and these are the markets bettors should try and avoid, instead trying to side with markets that closer to 100% and giving less of a margin to the bookmakers. In main markets such as moneyline and spread betting, the overround is typically low compared to prop bets such as to score the first basket because these prop bets have a higher variance so in order for the book to make consistent profit, they make the overround on these markets higher. Furthermore, in parlay bets, overround is compounded making the margins even greater for sportsbooks.

Using this calculator you can enter the prices of the events in a given market and produce the overround percentage of the market, showing you whether your pick and the market in total is offering a value opportunity.