How betting odds work

Odds look like a secret code at first. Once you can read them, they tell you two things at a glance: how much a bet pays, and roughly how likely the sportsbook thinks the outcome is. This guide covers the three formats you will see and how to read each one.

American odds

American odds are built around the number 100. Every price is either a positive number or a negative number.

A negative number is the favorite. It shows how much you would risk to win 100. A positive number is the underdog. It shows how much you would win if you risk 100.

In this made-up matchup, the Foxes are favored at -150. To win 100 in profit on the Foxes, you would risk 150. The Miners are the underdog at +130. A 100 risk on the Miners would return 130 in profit if they win. The 100 is just a reference point. The same ratios hold whether you stake 5 or 50.

Decimal odds

Decimal odds are common outside the United States and on many exchanges. The number represents your total return per unit staked, including your original stake.

A price of 2.50 means a 10 stake returns 25 in total: 15 in profit plus your 10 back. To find profit, subtract 1 from the decimal before multiplying. Here, 2.50 minus 1 is 1.50, so profit is 1.50 times your stake.

Fractional odds

Fractional odds show profit relative to stake as a fraction. Odds of 3/2 mean you win 3 for every 2 staked. Odds of 1/1, said as "evens," mean you win the same amount you stake. Fractional odds are most common in the United Kingdom and in horse racing.

Odds are a probability in disguise

The most useful habit a new bettor can build is reading odds as a statement about chance. Shorter odds on a favorite imply a higher chance of winning. Longer odds on an underdog imply a lower chance. Turning a price into a percentage is called finding the implied probability, and it is the foundation of judging whether a bet is worth making.