Glossary
Implied probability
Implied probability is the chance of an outcome that a set of odds represents, expressed as a percentage. Converting a price into implied probability lets you compare the sportsbook's view against your own, which is the core skill behind judging whether a bet offers value.
Every price is a probability wearing a costume. Implied probability is how you take the costume off.
For a minus price, the formula is the odds divided by the odds plus 100. A favorite at -200 gives 200 divided by 300, which is about 67 percent. For a plus price, it is 100 divided by the odds plus 100. An underdog at +150 gives 100 divided by 250, which is 40 percent.
Once you can do this, odds stop being a payout table and become a claim about the world. If you believe an outcome is more likely than its implied probability suggests, the price may offer value. If you believe it is less likely, the price is working against you. Because of the vig, the implied probabilities of all sides add up to more than 100 percent, so part of this skill is learning to strip that margin out before you compare.
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