How betting odds work: what they are and how to use them
Multiplying these probabilities by 100% gives the percentage. When probability is expressed as a number between 0 and 1, the relationships between probability p and odds are as follows. When Moneyline odds are quoted as a positive number +X, it means that a wager pays X to 100. However in many situations, the possible loss (“stake” or “wager”) is paid up front and, if the gambler wins, the net win plus the stake is returned. From local leagues to international tournaments, bookmakers our website shows the top price for every outcome before you bet.
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. Before a bet, check the archived results and historical odds of the teams or players involved, across leagues and tournaments worldwide. The value bets page compares the odds of each bookmaker with the average odds for the same outcome, highlighting the markets where one price stands out, with the probability included. OddsPortal has a number of betting tools that can bring your attention to interesting markets you may never have thought about betting on before, always with the best available price.
Moneyline bets are the simplest form of sports betting, focusing solely on picking a winner. Some bets involve combining multiple outcomes for higher rewards, while others target specific in-game events or achievements. Once you’re familiar with the basic math, fractional odds become an easy way to see potential profits relative to the stake. 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.
Opt in, deposit and bet £10 on any football market (odds 1/1+) within 7 days of sign up. Free bet – one-time stake of £50, min odds 1.5, stake not returned. Free stake not returned with winnings. Qualifying bets cannot be placed on a price boost. Qualifying bet must settle, excluding cash outs.
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.
However, not all fractional odds are traditionally read using the lowest common denominator (i.e. simplifying the fraction when possible). 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.
Fractions were traditionally used to bet on horse racing and were most popular 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.
A study on soccer betting found that the probability for the home team to win was generally about 3.4% less than the value calculated from the odds (for example, 46.6% for even odds). 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%.
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. If you’d like a bit more guidance, we have a full guide on how fractional odds work in betting. You may also see odds expressed with the lowest number first e.g. 1/2 or 2/7. Once you understand betting odds and the differences between them, reading them becomes easy.