How betting odds work: what they are and how to use them

In probability theory and statistics, odds and similar ratios may be more natural or more convenient than probabilities. Odds can also be expressed as a number, by dividing the terms in the ratio—in this case it bookies is unique (different fractions can represent the same rational number). For example, “odds of a weekend are 2 to 5”, while “chances of a weekend are 2 in 7”.

The same selection is priced differently by each bookmaker, so comparing bookmaker odds is the simplest way to make sure a winning bet pays out as much as possible.

With results, standings, predictions and the best odds on the same site, you can check the top price before every bet. We also compare prices on boxing and MMA, where big fights are added as soon as bookmakers publish odds, on esports and on rugby union, rugby league, baseball, volleyball, Aussie rules and many more. Our tennis odds page compares the prices on every match of the day, next to past results and the odds they closed at. In tennis we follow the ATP and WTA tours every week, the Challenger and ITF events in between and the four Grand Slams, from the Australian Open to Wimbledon and the US Open. For beginners, our bet calculator shows the payout of a bet, for a single or an accumulator, in decimal, fractional or American odds.

On the blocked odds page, you will be able to see matches or markets that online bookmakers are no longer offering odds for, which can signal a change in the market before other operators react to it. It is where the hot odds of the day show up first, and you can filter it by the last hour, 12 hours or 24 hours, by the percentage of bookies cutting their price and by market. The dropping odds page shows when the odds on a team, player or market have dropped before the start of a match. Whichever region you are playing from, there are multiple betting sites, or sportsbooks as they are called in the US, offering odds for each event and market on our site.

For instance, if the line is 220.5 in an NBA game, you’d bet on whether the teams’ combined score will be over 220 or under 220.5. Totals bets, also known as Over/Under bets, focus on the combined score of both teams rather than who wins. Point spread bets are all about leveling the playing field between teams, making any game more exciting.

By shifting the line, they encourage bettors to wager on the opposite side, helping maintain even exposure on both outcomes. They range from player stats, like total points scored by a star player, to quirky events like the length of the national anthem. Prop bets, short for proposition bets, focus on specific events or outcomes within a game, rather than the final score. Since these bets can be made months in advance, they offer a chance for big payouts, especially when backing underdogs. Instead of betting on a single game, you’re predicting outcomes like who will win the NBA championship, MVP award, or a division title. Bettors predict whether the total points scored will be above or below a set number.

In either case, having won, the bettor always receives the original stake back too; so if the odds are 4/1 the bettor receives a total of £500 (£400 plus the original £100). Favoured by bookmakers in the United Kingdom and Ireland, and also common in horse racing, fractional odds quote the net profit that will be paid out to the bettor, should they win, relative to the stake. That value may be regarded as the relative probability the event will happen, expressed as a fraction (if it is less than 1), or a multiple (if it is equal to or greater than one) of the likelihood that the event will not happen. The odds are a ratio of probabilities; an odds ratio is a ratio of odds, that is, a ratio of ratios of probabilities.

From local leagues to international tournaments, our website shows the top price for every outcome before you bet. OddsPortal is a free odds comparison site where you can compare betting odds from leading bookmakers on every match. Odds comparison, also known as line shopping, means checking the price of the same outcome at several bookmakers and taking the highest one.

The same price is 3/1 in fractional odds and +300 in American odds, which means a 100 bet wins 300 on top of the stake. This is a difficult task considering the huge teams of mathematicians that they employ. Moneyline, or American, odds are favoured by US bookmakers and punters, and are often expressed as positive and negative values (e.g. +250, -400). Bet £10+ on any sportsbook markets at odds of evens (2.00) or greater. “Double the odds” applies to fractional odds profits only, with extra winnings paid in cash on settlement. Get your initial stake back (up to £30) credited in set football markets.