Implied Probability Calculator
Convert American, decimal, and fractional odds to implied probability. Calculate no-vig fair odds, bookmaker margin, and batch convert multiple outcomes for sports betting analysis.
Enter odds above or click a preset to see the implied probability
Examples: +150, -110, 2.50, 1.91, 3/2, 10/11
Quick Reference: Odds to Probability
| American | Decimal | Fractional | Implied Probability |
|---|---|---|---|
| -500 | 1.20 | 1/5 | 83.3% |
| -300 | 1.33 | 1/3 | 75.0% |
| -200 | 1.50 | 1/2 | 66.7% |
| -150 | 1.67 | 2/3 | 60.0% |
| -110 | 1.91 | 10/11 | 52.4% |
| +100 | 2.00 | 1/1 | 50.0% |
| +150 | 2.50 | 3/2 | 40.0% |
| +200 | 3.00 | 2/1 | 33.3% |
| +300 | 4.00 | 3/1 | 25.0% |
| +500 | 6.00 | 5/1 | 16.7% |
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About This Calculator
"What are the actual chances of my bet winning?" This fundamental question separates profitable sports bettors from the rest. Betting odds aren't just numbers on a screen - they represent a bookmaker's assessment of probability, with their profit margin baked in. Understanding how to extract the true implied probability from any odds format is the foundation of value betting.
Our Implied Probability Calculator instantly converts American (+150, -110), decimal (2.50), and fractional (3/2) odds into their underlying probability percentages. But we go further: our no-vig calculator removes the bookmaker's margin to reveal fair odds, helping you identify when you're getting true value. With batch conversion for multiple outcomes and quick presets for common odds, you can analyze entire markets in seconds.
Whether you're betting on NFL moneylines, Premier League match odds, or UFC fight outcomes, knowing the implied probability is essential. The global sports betting market exceeds $200 billion annually, yet most bettors place wagers without understanding the mathematics behind the odds. A bet at -110 implies a 52.4% probability - not 50%. That 2.4% difference is the bookmaker's edge, and it's the reason the house always wins unless you learn to identify true value.
How to Use the Implied Probability Calculator
- 1**Enter your odds**: Input odds in any format - American (+150, -110), decimal (2.50), or fractional (3/2).
- 2**View implied probability**: Instantly see the percentage probability the odds represent.
- 3**Use quick presets**: Click common odds buttons (-110, +150, +200, etc.) for instant conversion.
- 4**Calculate no-vig odds**: Enter multiple outcomes to see true probabilities with the bookmaker margin removed.
- 5**Analyze the vig**: View the total overround/margin the bookmaker is charging on the market.
- 6**Batch convert outcomes**: Enter all outcomes in a multi-way market to see fair odds for each.
- 7**Compare to your estimate**: If your probability estimate exceeds the implied probability, you have a value bet.
Formula
Implied Probability = 1 / Decimal Odds x 100This elegant formula reveals the probability hidden within any odds format. For decimal odds of 2.50, the implied probability is (1/2.50) x 100 = 40%. For American odds, first convert to decimal: positive odds become (odds/100) + 1, negative odds become (100/|odds|) + 1. For fractional odds like 3/2, convert to decimal by dividing (3/2) + 1 = 2.50. The sum of implied probabilities for all outcomes in a market reveals the bookmaker's margin - a 105% total means a 5% vig.
Understanding Implied Probability
What Is Implied Probability?
Implied probability is the percentage chance of an outcome occurring as suggested by the betting odds. It's "implied" because bookmakers don't publish raw probabilities - they publish odds that include their profit margin. Extracting the true probability requires understanding this relationship.
The Core Concept:
- Odds of +200 imply a 33.3% chance of winning
- Odds of -200 imply a 66.7% chance of winning
- Odds of +100 (even money) imply a 50% chance
Why It Matters: Successful betting isn't about picking winners - it's about finding mispriced odds. If you believe a team has a 45% chance to win but the odds imply only 35%, you've found value. The 10% edge compounds over hundreds of bets into significant profit.
Implied Probability by Odds Format:
| American | Decimal | Fractional | Implied Probability |
|---|---|---|---|
| -500 | 1.20 | 1/5 | 83.3% |
| -300 | 1.33 | 1/3 | 75.0% |
| -200 | 1.50 | 1/2 | 66.7% |
| -150 | 1.67 | 2/3 | 60.0% |
| -110 | 1.91 | 10/11 | 52.4% |
| +100 | 2.00 | 1/1 | 50.0% |
| +150 | 2.50 | 3/2 | 40.0% |
| +200 | 3.00 | 2/1 | 33.3% |
| +300 | 4.00 | 3/1 | 25.0% |
| +500 | 6.00 | 5/1 | 16.7% |
| +1000 | 11.00 | 10/1 | 9.1% |
Converting American Odds to Probability
American Odds Explained
American odds (also called moneyline odds) use + and - signs relative to $100:
- Negative odds (-150): Amount you must risk to win $100
- Positive odds (+150): Amount you win on a $100 bet
Conversion Formulas:
For Negative American Odds:
Implied Probability = |Odds| / (|Odds| + 100) x 100
Example: -150 odds
- Calculation: 150 / (150 + 100) x 100
- Result: 150 / 250 x 100 = 60%
For Positive American Odds:
Implied Probability = 100 / (Odds + 100) x 100
Example: +200 odds
- Calculation: 100 / (200 + 100) x 100
- Result: 100 / 300 x 100 = 33.3%
Quick Reference:
| American Odds | Formula | Implied Probability |
|---|---|---|
| -400 | 400/500 | 80.0% |
| -250 | 250/350 | 71.4% |
| -150 | 150/250 | 60.0% |
| -110 | 110/210 | 52.4% |
| +110 | 100/210 | 47.6% |
| +150 | 100/250 | 40.0% |
| +250 | 100/350 | 28.6% |
| +400 | 100/500 | 20.0% |
Converting Decimal Odds to Probability
Decimal Odds: The Global Standard
Decimal odds represent your total return per unit bet, including your stake. They're the simplest format for probability calculation:
Conversion Formula:
Implied Probability = (1 / Decimal Odds) x 100
Examples:
| Decimal Odds | Calculation | Implied Probability |
|---|---|---|
| 1.25 | 1/1.25 x 100 | 80.0% |
| 1.50 | 1/1.50 x 100 | 66.7% |
| 1.80 | 1/1.80 x 100 | 55.6% |
| 1.91 | 1/1.91 x 100 | 52.4% |
| 2.00 | 1/2.00 x 100 | 50.0% |
| 2.50 | 1/2.50 x 100 | 40.0% |
| 3.00 | 1/3.00 x 100 | 33.3% |
| 4.00 | 1/4.00 x 100 | 25.0% |
| 5.00 | 1/5.00 x 100 | 20.0% |
| 10.00 | 1/10.00 x 100 | 10.0% |
Why Decimal Odds Are Popular:
- Simple probability calculation: Just divide 1 by the odds
- Easy payout calculation: Stake x Odds = Total Return
- Parlay-friendly: Multiply all odds together for combined payout
- No conversion needed: Works identically for favorites and underdogs
Converting Fractional Odds to Probability
Fractional Odds: The Traditional Format
Popular in UK horse racing and traditional bookmakers, fractional odds show profit relative to stake:
- 5/1 = Win $5 for every $1 staked
- 1/5 = Win $1 for every $5 staked (odds-on favorite)
Conversion Formula:
Implied Probability = Denominator / (Numerator + Denominator) x 100
Examples:
| Fractional | Calculation | Implied Probability |
|---|---|---|
| 1/5 | 5/(1+5) x 100 | 83.3% |
| 1/3 | 3/(1+3) x 100 | 75.0% |
| 1/2 | 2/(1+2) x 100 | 66.7% |
| 4/6 | 6/(4+6) x 100 | 60.0% |
| Evens (1/1) | 1/(1+1) x 100 | 50.0% |
| 6/4 | 4/(6+4) x 100 | 40.0% |
| 2/1 | 1/(2+1) x 100 | 33.3% |
| 3/1 | 1/(3+1) x 100 | 25.0% |
| 5/1 | 1/(5+1) x 100 | 16.7% |
| 10/1 | 1/(10+1) x 100 | 9.1% |
Converting Fractional to Decimal (Then to Probability):
Decimal = (Numerator / Denominator) + 1
Example: 5/2 = (5/2) + 1 = 3.50 decimal
The No-Vig (Fair Odds) Calculator
What Are No-Vig Odds?
No-vig (or "vig-free") odds remove the bookmaker's profit margin to show the true market probability. This reveals what the odds would be in a perfectly efficient market with zero commission.
Why Calculate No-Vig Odds:
- Identify the true probability: See what bookmakers actually think will happen
- Find value bets: Compare no-vig odds to your own estimates
- Compare across sportsbooks: The book with odds closest to no-vig is offering the best value
- Understand the vig: Know exactly how much you're paying in commission
Calculation Method:
- Convert all odds to implied probability
- Sum the total implied probability (this exceeds 100%)
- Divide each probability by the total to normalize to 100%
- Convert back to odds
Example: NFL Point Spread
Original odds: Team A -110, Team B -110
Step 1 - Calculate implied probabilities:
- Team A: 110/210 = 52.38%
- Team B: 110/210 = 52.38%
- Total: 104.76%
Step 2 - Remove the vig (normalize to 100%):
- Team A: 52.38% / 104.76% x 100 = 50%
- Team B: 52.38% / 104.76% x 100 = 50%
Step 3 - Convert to fair odds:
- Team A: +100 (from 50%)
- Team B: +100 (from 50%)
The "true" odds are even money; the vig is 4.76%.
Calculating Bookmaker Margin (Vig)
Understanding the Vig
The vig (vigorish), also called juice, margin, or overround, is the bookmaker's guaranteed profit. It's built into every market by setting odds that sum to more than 100% implied probability.
Vig Calculation:
Vig = (Sum of Implied Probabilities) - 100%
Example Markets:
| Market Type | Typical Vig | Implied Total |
|---|---|---|
| NFL spread (-110/-110) | 4.76% | 104.76% |
| MLB moneyline | 3-5% | 103-105% |
| Soccer 3-way | 5-8% | 105-108% |
| Player props | 8-15% | 108-115% |
| Futures/outrights | 15-40% | 115-140% |
Real-World Example: Soccer Match
Odds offered:
- Home win: 2.20 (45.5% implied)
- Draw: 3.40 (29.4% implied)
- Away win: 3.10 (32.3% implied)
Total implied: 45.5% + 29.4% + 32.3% = 107.2%
Vig: 107.2% - 100% = 7.2%
Impact on Bettors:
At a 5% vig, you need to win approximately:
- 52.5% at even odds to break even
- 55% to achieve 5% ROI
- 60% to achieve 15% ROI
The vig is why casual bettors lose over time and why finding low-vig markets is crucial for profitability.
Batch Conversion for Multi-Way Markets
Why Batch Convert?
Many betting markets have more than two outcomes - golf tournaments, NASCAR races, Premier League title futures, and more. Our batch conversion tool lets you enter all outcomes at once to:
- See fair probability for every outcome
- Calculate the total market vig
- Identify which outcomes offer the best value
- Compare to your own probability estimates
Example: 4-Team Division Winner Futures
Original odds:
- Team A: +150 (40.0% implied)
- Team B: +200 (33.3% implied)
- Team C: +300 (25.0% implied)
- Team D: +500 (16.7% implied)
Total implied: 115.0% (15% vig)
No-vig probabilities:
- Team A: 40.0/115.0 = 34.8%
- Team B: 33.3/115.0 = 29.0%
- Team C: 25.0/115.0 = 21.7%
- Team D: 16.7/115.0 = 14.5%
Fair odds (no-vig):
- Team A: +187 (from 34.8%)
- Team B: +245 (from 29.0%)
- Team C: +361 (from 21.7%)
- Team D: +590 (from 14.5%)
Interpretation: The vig is spread across all outcomes. Team A's offered +150 should be +187 at fair odds - you're giving up 37 cents of value. If you believe Team A has a 40% chance (matching the raw implied probability), you're actually getting slightly negative value because the true probability is 34.8%.
Using Implied Probability for Value Betting
The Value Betting Framework
Value betting is the only sustainable path to long-term sports betting profit. It requires:
- Calculate implied probability from the offered odds
- Estimate your own probability using research, models, or expertise
- Compare: Your probability > Implied probability = Value
- Calculate edge: Your % - Implied % = Edge
- Size your bet: Use Kelly Criterion for optimal bankroll growth
Example Value Bet Analysis:
Scenario: NBA game, Team A at +150 (40% implied) Your Analysis: Team A has 48% chance based on your model
Value Check:
- Your probability: 48%
- Implied probability: 40%
- Edge: 48% - 40% = 8% edge
Expected Value Calculation: EV = (Win Probability x Profit) - (Lose Probability x Stake) EV = (0.48 x $150) - (0.52 x $100) EV = $72 - $52 = +$20 per $100 bet
Why This Works Long-Term:
Even if Team A loses this specific game, betting +8% edges consistently will profit over hundreds of bets. The math is the same as a casino's edge - except you're the house when you find value.
Red Flags (Not Value):
- Betting favorites you "feel good about" without calculating edge
- Following tipsters without understanding their probability assessments
- Assuming longshots are always value (high odds often reflect high risk accurately)
- Ignoring the vig when comparing your estimates
Pro Tips
- 💡Always calculate implied probability before placing any bet - if you cannot articulate the implied probability, you should not be betting.
- 💡At -110 odds (standard juice), you need to win 52.4% of bets to break even. Every bet must overcome this hurdle.
- 💡Use no-vig calculations to see the true market probability and identify which sportsbook offers the best value.
- 💡The vig on player props and futures is typically 2-3x higher than point spreads - be extra selective with these markets.
- 💡Compare your probability estimates to implied probability, not to the odds themselves. A +300 longshot is not automatically good value.
- 💡Lower decimal odds mean higher implied probability. Anything below 2.00 implies a greater than 50% chance.
- 💡Batch convert multi-way markets (like golf or NASCAR) to see how the vig is distributed across all outcomes.
- 💡True value betting means betting when your probability exceeds implied probability, regardless of whether you "like" the team.
- 💡Track your expected value over time, not just wins and losses. Consistent +EV bets will profit long-term.
- 💡Betting exchanges typically have lower vig than traditional sportsbooks - consider them for better implied probability.
- 💡The closing line (final odds before event) is often the most accurate probability estimate. Beating it consistently predicts profit.
- 💡Use implied probability to calculate break-even win rates at any odds. At +200, you need just 33.3% wins to profit.
Frequently Asked Questions
For negative American odds (like -150), use: Probability = |Odds| / (|Odds| + 100). So -150 becomes 150/250 = 60%. For positive American odds (like +200), use: Probability = 100 / (Odds + 100). So +200 becomes 100/300 = 33.3%. The key insight is that negative odds always yield probabilities above 50% (favorites), while positive odds yield probabilities below 50% (underdogs). At even money (+100 or -100), the implied probability is exactly 50%.
