Odds, Probability & Bankroll
Betting odds
Betting odds are the prices a bookmaker sets for a wager. They determine how much a winning bet pays out and also reflect the bookmaker's view of how likely an outcome is.
Key points
- Odds are set before an event and are called fixed odds; the payout is locked in at the time of the bet. 3
- The three main formats — decimal, fractional, and American — are used in different regions; decimal is common in Europe, fractional in the UK, and American in the US. 12
- A bettor places a stake at the quoted odds; if the selection wins, the payout is calculated from the odds format, otherwise the stake is lost. 36
- Odds can be converted into an implied probability for comparison with the event's actual chance of occurring. 15
Common odds formats
| Format | Example | Meaning |
|---|---|---|
| Decimal | 2.00 | Total payout of 2.00 for every 1.00 staked |
| Fractional | 1/1 | Profit of 1.00 for every 1.00 staked |
| American | 100 | Bet 100 to win 100 (profit) |
How to read betting odds
- Identify the format: decimal (e.g. 1.50), fractional (e.g. 1/2), or American (e.g. -200 or +150).
- For decimal odds, multiply your stake by the number to get total return. For fractional odds, multiply your stake by the fraction to get profit. For American odds, a negative number shows the stake needed to win 100; a positive number shows profit on a 100 stake.
- Compare the implied probability (1 divided by decimal odds) with your own assessment of the event's chance to decide if the bet offers value.
Common questions
What are the betting odds for the super bowl?
Super Bowl odds change constantly as the season progresses and bets are placed. They are typically quoted in American format (e.g. +500 for a longshot) and can be found on any major sportsbook site.
What are good betting odds?
Good betting odds are those where the implied probability is lower than your own estimate of the event's true chance. This is called finding value. There is no fixed number; it depends on the market and the event.
What do sports betting odds mean?
Sports betting odds are the prices set by a bookmaker for a given outcome. They tell you how much you can win from a bet and, when converted, the bookmaker's implied probability of that outcome happening.
What do betting odds numbers mean?
The numbers represent the payout or stake required. In decimal odds, the number is the total return per unit stake. In fractional odds, the first number is profit, the second is stake. In American odds, the number shows either the stake needed to win 100 (negative) or the profit on a 100 stake (positive).
Where this term is used
Not the same as
- Betting odds to probability — a conversion method, not the odds themselves
- Futures betting odds — odds for events far in the future, a subset of betting odds
- Negative betting odds explained — a specific American odds format, not the general term
- Sports betting odds explained — an explanatory phrase for the same concept in sports contexts
- Betting odds explained football — the same concept applied to football markets
- Betting odds spread explained — a different concept involving point spreads, not the odds themselves
Related terms
Sources
- Odds - Wikipedia en.wikipedia.org General definition and overview of odds formats.
- Sports betting - Wikipedia en.wikipedia.org Definition of betting odds and examples of even-money bets.
- Fixed-odds betting - Wikipedia en.wikipedia.org Fixed-odds betting definition and how payouts work.
- Mathematics of bookmaking - Wikipedia en.wikipedia.org Mathematics of bookmaking, including the relationship between odds and probability.
- Inferring Tennis Match Progress from In-Play Betting Odds doc.ic.ac.uk Decimal odds as reciprocal of probability.
- [PDF] Sports betting 1 bristol.ac.uk Explanation of how a bettor's stake is handled on a win or loss.
Sources are drawn from regulators, universities and published research, and each one is labelled with what it actually is — a preprint is not called a paper. Bookmaker and affiliate pages are never cited here, because a page that sells betting is not a neutral authority on it.