Implied Probability Calculator
Convert betting odds to win probability percentage and understand what the odds really mean
Formula:IP = 1 / Decimal Odds
Quick Examples
How to Calculate Implied Probability
Implied probability = 1 / decimal odds × 100. For -150 American odds (1.67 decimal): 1/1.67 = 60%. For +200 American (3.0 decimal): 1/3.0 = 33.3%. The sportsbook prices these outcomes at 60% and 33.3% likelihood respectively. Note: Sum of implied probabilities typically exceeds 100% due to the bookmaker's margin (vig).
Key Facts
- ✓Implied probability shows what win rate you need to break even at given odds
- ✓-110 odds imply 52.4% probability, meaning you need >52.4% win rate to profit
- ✓Total implied probability on a 2-way market typically equals 104-108% (the excess is vig)
- ✓True probability ≠ implied probability due to bookmaker margin
- ✓+EV bets occur when your estimated probability exceeds implied probability
- ✓Convert American to decimal first: positive odds ÷ 100 + 1, negative odds: 100 ÷ |odds| + 1
Common Odds Reference
| American | Decimal | Implied Prob. |
|---|---|---|
| -500 | 1.20 | 83.3% |
| -200 | 1.50 | 66.7% |
| -150 | 1.67 | 60.0% |
| -110 | 1.91 | 52.4% |
| +100 | 2.00 | 50.0% |
| +150 | 2.50 | 40.0% |
| +200 | 3.00 | 33.3% |
| +300 | 4.00 | 25.0% |
| +500 | 6.00 | 16.7% |
Frequently Asked Questions
What is implied probability?▼
Implied probability is the likelihood of an outcome as suggested by the betting odds. It represents what win rate you would need at those odds to break even over time. Bookmakers set odds based on their estimated probabilities plus a margin for profit.
How does vig affect implied probability?▼
The vig (vigorish or juice) is the bookmaker's margin built into the odds. In a fair market, both sides of a coin flip would be +100 (50% each). But sportsbooks typically offer -110 on both sides (52.4% each), totaling 104.8%. The 4.8% excess is the vig, meaning implied probabilities are inflated from true probabilities.
How do I calculate true probability vs implied probability?▼
True probability is your honest assessment of likelihood based on analysis. Implied probability is what the odds suggest. If you believe a team has 60% chance to win but the implied probability is 55%, you have an edge (+EV). Calculate by removing vig: divide each implied probability by the total (e.g., 52.4/104.8 = 50% no-vig).
How do I read implied probability from American odds?▼
For negative odds: Implied % = |odds| / (|odds| + 100). For -200: 200/(200+100) = 66.7%. For positive odds: Implied % = 100 / (odds + 100). For +150: 100/(150+100) = 40%. These formulas help you quickly assess what the sportsbook thinks.
How this works
Calculations follow the published mathematics of the game — combinatorics for cards, probability theory for dice, and expected-value accounting for wagers. Results are verified against independent references (primarily Wizard of Odds). No calculation here is an opinion or recommendation; it is arithmetic applied to the rules of the game.
What this tool can’t do
When to consult a professional
This tool computes probability and expected value. It is not a betting system and cannot predict the outcome of any individual wager. If gambling is causing problems for you or someone you know, call the National Problem Gambling Helpline at 1-800-GAMBLER.
Sources
- [1]Wizard of Odds — Michael Shackleford, ASAIndustrywizardofodds.comAccessed Apr 21, 2026
Actuary; widely cited casino-game probability reference. Used for house-edge and EV verification.
- [2]National Council on Problem GamblingOfficial sourcencpgambling.orgAccessed Apr 21, 2026
Responsible-gambling guidance and 1-800-GAMBLER helpline.
Joseph OrdunaFounder & Software Engineer
Full-stack software engineer specializing in embedded systems, web architecture, and AI/ML. Founder of Practical Web Tools. Built the gesture-controlled drone IP acquired by KD Interactive (Aura Drone, sold on Amazon).