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

Fractions were traditionally used to bet on horse racing and were most popular bookies in high street betting shops in the UK, before the advent of internet gambling. Betting odds are usually expressed either as fractions (e.g. ‘3/1’) or as decimals (e.g. 4.0). All of these have different possibilities, probabilities, chances – or odds – of happening. They give you a quick indication of how much you could expect to win if your bet wins.

The issue with betting odds is that they’re always tipped in the bookmakers’ favour to allow them to make a profit. Because of the many factors involved, it is impossible to calculate exact probability in sports betting. In betting terms, probability is odds expressed as a percentage. Moneyline odds use $100 as the evens line, with either positive or negative outcomes.

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. 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.

The numerator and denominator of fractional odds are often integers, thus if the bookmaker’s payout was to be £1.25 profit for every £1 stake, this would be equivalent to £5 profit for every £4 staked, and the odds would therefore be expressed as 5/4. Before you rely on one, check how many bookmakers it covers, how quickly the prices are refreshed, whether it shows markets beyond the match result and whether it keeps the history of every price move. If you are new to sports betting or have been betting for years, the betting odds today shown for each match tell you where every price is best, so a winning bet always pays out as much as it can. Open our American football odds page for the next games, with past results and the prices they closed at. We cover the NHL, the SHL in Sweden and the KHL among many hockey leagues, with prices on single games and on the outright winners. Basketball goes from NBA odds and the EuroLeague to domestic leagues such as the Super Lig in Turkey and the LNB in France, with prices on single games and on the outright winners.

They’re especially popular in horse racing, where bettors often look for value in underdog picks or assess returns more precisely using this format. Fractional odds can be a bit trickier to calculate quickly, but they’re favored by many bettors for how clearly they represent the risk-reward ratio. If you bet $10 at 7/2, you’d get $35 in profit plus your initial $10 back, totaling $45.

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. Free bets valid 7 days from individual release, stake not returned, no cash out.

When a large number of casual bettors, often called “public” bettors, place money on one side, the line may shift to reflect this surge in interest. 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. For example, if a team is -5.5, they need to win by 6 or more points to win the bet. Instead of just picking a winner, you’re betting on whether a team can “cover the spread,” meaning they either win by a certain margin or avoid losing by too much.

The total of these three percentages is 100%, thus representing a fair ‘book’. In a 3-horse race, for example, the true probabilities of each of the horses winning based on their relative abilities may be 50%, 40% and 10%. In formulating the odds to display the bookmaker will have included a profit margin which effectively means that the payout to a successful bettor is less than that represented by the true chance of the event occurring. In gambling, the odds on display do not represent the true chances (as imagined by the bookmaker) that the event will or will not occur, but are the amount that the bookmaker will pay out on a winning bet, together with the required stake. In most cases, the favorite will have negative moneyline odds (less payoff for a safer bet) and the underdog will have positive moneyline odds (more payoff for a risky bet). A “moneyline” wager refers to odds on the straight-up outcome of a game with no consideration to a point spread.