Implied Probability — How to Convert Moneyline Odds to Win Percentages
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Implied probability is the win percentage hidden inside any set of odds. Convert the number correctly and you know exactly what the sportsbook thinks each side is worth — then you can decide whether the price is fair.
What Is Implied Probability on a Moneyline Bet?
Every moneyline price carries a built-in win probability. A -300 favorite implies roughly a 75% chance of winning. A +200 underdog implies about 33.3%. These aren't opinions — they're math.
The formulas are simple. I use them constantly when evaluating whether a line has any value.
- Negative odds: |odds| ÷ (|odds| + 100)
- Positive odds: 100 ÷ (odds + 100)
How Do You Calculate Implied Probability from Moneyline Odds?
Run the numbers on a few common lines:
| Moneyline | Side | Formula | Implied Probability |
|---|---|---|---|
| -200 | Favorite | 200 ÷ (200 + 100) | ~66.7% |
| -300 | Favorite | 300 ÷ (300 + 100) | 75.0% |
| -500 | Favorite | 500 ÷ (500 + 100) | ~83.3% |
| +160 | Underdog | 100 ÷ (160 + 100) | ~38.5% |
| +200 | Underdog | 100 ÷ (200 + 100) | ~33.3% |
Notice that the two sides of any line don't add up to 100%. They add up to something like 104%–110%. That gap is the vig. For a full breakdown of how that margin works, read the page on vig and juice on moneylines — what the sportsbook keeps from every bet.
Why Does Implied Probability Matter for Value Betting?
Implied probability tells you the break-even win rate for any bet. If you think a team has a 70% real chance of winning and the line implies 66.7% (-200), that's a value bet. If the line implies 75% (-300) and your honest estimate is 70%, skip it.
To break even on a -300 moneyline, you must win more than 75% of the time. That's a very high bar. Most bettors underestimate it. See the full payout math at moneyline payouts — what you actually win at each odds level.
I've watched sharp bettors pass on heavy favorites at -400 or -500 for exactly this reason. The implied probability leaves almost no margin for error.
Pick 'Em Games and Implied Probability
When both teams are priced at -110, each side implies about 52.4% — not 50%. The extra 2.4% per side is the book's edge. A true 50/50 coin flip would price out at +100 / +100 with no vig at all. That almost never happens on a licensed sportsbook.
Understanding this is especially useful when you start line shopping moneylines to find the best price across multiple books. Even small differences in implied probability compound over hundreds of bets.
Applying Implied Probability Before You Bet
Before placing any moneyline wager, run the formula. Compare the implied probability to your own estimate of the true win percentage. If the implied number is higher than your estimate, the bet has negative expected value. Walk away.
For deeper context on how odds are structured sport by sport, check the moneyline markets by sport — NFL, MLB, NBA, soccer section. Must be 21+ in most states (18+ in some). Gambling problem? Call 1-800-GAMBLER.