Odds

TL;DR

• A way to express how likely an event is by comparing chances of occurrence versus non-occurrence.
• Common in gambling and betting; can be given as a ratio, percentage, decimal odds, or moneyline odds.
• Odds do not guarantee outcomes and are not identical to probability.

Definition

Odds are a way of expressing the probability or likelihood of an event occurring, often used in gambling and betting to determine the chances of a particular outcome occurring.

Explanation

• Odds express the ratio of the likelihood that an event will occur to the likelihood that it will not occur.
• They can be represented in multiple formats: as a ratio (e.g., “2 to 1”), as a percentage, as decimal odds, or as moneyline odds.
• Decimal odds represent the total amount returned on a successful bet, including the original stake. For example, decimal odds of 2.00 mean that for every $1 bet the player will receive$2 in return if they win.
• Moneyline odds represent the amount won on a successful bet. For example, moneyline odds of +100 mean that for every $100 bet, the player will win$100 in return if they win.
• Odds are related to probability but are not the same: probability is typically expressed as a decimal or percentage, while odds are a ratio comparing occurrence to non-occurrence.

Examples

General ratio example

If the odds of winning a bet are $2 \text{ to } 1$, this means that for every two times the event does not occur, it will occur once.

Roulette

In roulette there are 38 numbers on the wheel, with 18 red, 18 black, and two green. If you bet on red, the odds are given as $18 \text{ to } 20$, or $1 \text{ to } 1$. The percentage chance is 47.37% because there are 18 red numbers out of 38 total numbers on the wheel.

Blackjack

In blackjack, the odds of being dealt a natural blackjack (an ace and a ten) are given as $4 \text{ to } 13$, or $1 \text{ to } 3$. The percentage chance is 30.77% because there are 4 natural blackjacks out of 13 total possible hands.

Decimal and moneyline examples

• Decimal odds example: decimal odds of 2.00 mean that for every $1 bet, the player will receive$2 in return if they win.
• Moneyline odds example: moneyline odds of +100 mean that for every $100 bet, the player will win$100 in return if they win.

Use cases

• Widely used in gambling and betting to determine the chances of particular outcomes.

Notes or pitfalls

• Odds do not guarantee that an event will occur; they only express likelihood.
• Odds are not the same as probability. For example, the probability of winning a bet on red in roulette is 47.37%, while the odds are expressed as $1 \text{ to } 1$ in the example above.

Related terms

• Probability
• Decimal odds
• Moneyline odds