Gambling terms, explained straight

Odds, Probability & Bankroll

American odds to implied probability

The process of turning a moneyline price into the break-even percentage that outcome must have for the bet to be fair.

Formula (negative odds)
Implied probability = |Odds| / (|Odds| + 100)1
Formula (positive odds)
Implied probability = 100 / (Odds + 100)1
Example
-150 odds → 60% implied probability; +200 odds → 33.3%1

Key points

  • Negative odds state how much to risk to win $100; positive odds state profit on a $100 stake.1
  • The conversion yields the bookmaker's implied probability, not the true probability of the event.12
  • The formulas apply only to American odds, not to decimal or fractional formats.13

Where this term is used

Sources

  1. Player Props: Understanding the Math Behind the Lines wizardofodds.com Provides the exact formulas for converting American odds to implied probability and the worked examples.
  2. Ask The Wizard #412 wizardofodds.com Supports the point that the result is an implied probability, not the true probability.
  3. Sports betting - Wikipedia en.wikipedia.org Confirms that American odds are a distinct format with its own conversion method.

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.