Implied Probability Calculator
Convert American odds to a break-even win rate - then strip the vig to see the fair number.
At -110 you must win 52.38% of the time just to break even.
The raw implied probabilities sum to 104.76%. That overround is the sportsbook margin.
Quick Answer
Implied probability converts betting odds into the break-even win rate before removing sportsbook margin. For positive American odds, divide 100 by the odds plus 100. For negative odds, divide the absolute odds by the absolute odds plus 100. At -110 the implied probability is 52.38%; at +150 it is 40%.
Free calculator: Skip the math — use the Implied Probability Calculator on this page to convert any American (+/−), decimal, or fractional odds to a win% instantly.
Implied probability is the win rate that a betting odds line says is “fair.” For positive American odds (+150), implied probability = 100 ÷ (odds + 100) = 40%. For negative odds (−150), implied probability = odds ÷ (odds + 100) = 60%. When your true projected probability is higher than the implied probability, the bet has positive expected value and is worth taking.
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What Is Implied Probability?
Every set of betting odds carries an embedded “fair” probability that the bet wins. Convert the odds into a percentage and you’ve found the implied probability — the win rate the sportsbook is pricing in. Beat that implied probability with your own model, and you have an edge.
The key insight: implied probability is the inverse of the odds you receive. If a team is +200 (decimal 3.00), the book is saying they’ll win roughly 1 time in 3 attempts. Bet on them only if you believe they’ll win more often than that.
How to Calculate Implied Probability from American Odds
Positive odds (underdog)
Formula: 100 ÷ (odds + 100)
- +100 → 100 ÷ 200 = 50.0%
- +150 → 100 ÷ 250 = 40.0%
- +200 → 100 ÷ 300 = 33.3%
- +300 → 100 ÷ 400 = 25.0%
- +500 → 100 ÷ 600 = 16.7%
Negative odds (favorite)
Formula: odds ÷ (odds + 100) (using absolute value of odds)
- −110 → 110 ÷ 210 = 52.4%
- −150 → 150 ÷ 250 = 60.0%
- −200 → 200 ÷ 300 = 66.7%
- −300 → 300 ÷ 400 = 75.0%
- −500 → 500 ÷ 600 = 83.3%
Decimal odds
For decimal odds: implied probability = 1 ÷ decimal odds
- 1.50 decimal → 1 ÷ 1.50 = 66.7% (equivalent to −200 American)
- 2.00 decimal → 1 ÷ 2.00 = 50.0% (equivalent to +100 American)
- 3.00 decimal → 1 ÷ 3.00 = 33.3% (equivalent to +200 American)
Use PropsBot’s Odds Converter to translate between American, decimal, fractional, and implied probability instantly.
Implied Probability, Vig, and the Sportsbook’s Edge
Here’s a critical detail many bettors miss: the sum of implied probabilities across all outcomes of an event is always greater than 100%. That excess is the sportsbook’s vig (also called juice or hold).
Example: A coin-flip market priced as −110 / −110:
- Heads at −110 → implied probability = 52.4%
- Tails at −110 → implied probability = 52.4%
- Total: 104.8%
That extra 4.8% is the sportsbook’s house edge. To find the “true” no-vig fair probability, divide each implied probability by the total. In this example: 52.4% ÷ 104.8% = 50.0% — the actual fair probability of heads.
When you compare your model’s projection to a book’s price, always remove the vig first. PropsBot’s Odds Converter converts one price at a time; to remove the vig, use the Remove the vig tab in the calculator at the top of this page.
Using Implied Probability to Find Value
The single most useful application of implied probability is finding +EV bets. Three steps:
- Calculate the implied probability of the line offered.
- Remove the vig to get the fair implied probability.
- Compare to your model’s true probability. The no-vig number shows how far you disagree with the market; the bet has positive expected value only if your projected probability is also higher than the implied probability of the price you actually bet (step 1).
Worked example for an NFL player prop:
- Player A: Over 75.5 receiving yards at −115. Implied probability: 53.5%. Removing vig (assume total ~109%) → fair ~49.1%.
- PropsBot’s model projects Player A’s true probability of going over: 57%.
- Edge: 57% − 49.1% = +7.9 percentage points. Bet has positive EV because 57% also beats the 53.5% break-even of the -115 price; the margin over break-even is 3.5 points.
This is exactly how PropsBot’s AI scores every prop on every slate — convert the line to no-vig implied probability, compare to model projection, flag positive-edge bets. Read more about positive expected value and closing line value as complementary signals.
Convert Implied Probability Back to Odds
Need to go the other direction — your model says 55% true probability, what’s the fair line?
Decimal odds: 1 ÷ probability → 1 ÷ 0.55 = 1.818
American odds (when prob > 50%): −(probability × 100) ÷ (1 − probability) → −(0.55 × 100) ÷ 0.45 = −122
American odds (when prob < 50%): (1 − probability) × 100 ÷ probability → e.g., 45% → 0.55 × 100 ÷ 0.45 = +122
If a book offers you better than your fair line (e.g., they’re at −115 and your fair is −122), the bet is +EV.
Frequently Asked Questions
What is implied probability in betting?
Implied probability is the win rate the betting odds suggest is “fair.” Convert American odds with: for positive odds, 100 ÷ (odds + 100); for negative odds, odds ÷ (odds + 100). For decimal odds, divide 1 by the decimal. Implied probability greater than your model’s true probability means the bet is negative EV.
How do you calculate implied probability from American odds?
For positive American odds (+150): 100 ÷ (150 + 100) = 40%. For negative American odds (−150): 150 ÷ (150 + 100) = 60%. Always include 100 in the denominator — that’s the standard formula.
Why does total implied probability exceed 100%?
The excess above 100% is the sportsbook’s vig (also called juice or hold). On a typical −110/−110 market, total implied probability is 104.8%, meaning the book takes a 4.8% house edge. To find true fair probability, divide each side by the total.
What is the difference between implied probability and true probability?
Implied probability is what the book’s odds imply. True probability is your independent estimate (from a model, projections, or analysis) of the bet’s actual win rate. You have positive expected value when your true probability is higher than the implied probability of the price you bet; the no-vig probability shows how far you disagree with the market.
How do I convert implied probability to American odds?
For probabilities greater than 50%, American odds = −(probability × 100) ÷ (1 − probability). For probabilities less than 50%, American odds = (1 − probability) × 100 ÷ probability. A 60% probability translates to −150; a 40% probability translates to +150.
Does PropsBot use implied probability to find bets?
Yes. PropsBot’s AI converts every prop line to no-vig implied probability, compares it to the model’s projected true probability, and ranks bets by edge. On the public ledger, as of September 29, 2026, the NFL High ROI signal shows 16.8% ROI on 8,571 graded picks and the NBA High ROI signal shows 25.9% ROI on 81,410; that is the implied-probability vs. model-projection method graded in public.
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Related Glossary Terms
- Betting Handle Explained
- Hedging in Sports Betting
- Cover the Spread, Explained
- Middling in Sports Betting
Related PropsBot Research
Continue with the market or tool that matches the decision you are researching:
- odds converter (any format, with payout)
- no-vig fair odds calculator
- expected value calculator
- odds converter
Implied probability chart: American, fractional and decimal odds
Implied probability is 1 divided by the decimal odds. It is the break-even win rate for that price, before any vig is removed. Decimal odds are rounded to three places and probabilities to one decimal place.
| American odds | Fractional odds | Decimal odds | Implied probability |
|---|---|---|---|
| -1000 | 1/10 | 1.100 | 90.9% |
| -500 | 1/5 | 1.200 | 83.3% |
| -400 | 1/4 | 1.250 | 80.0% |
| -300 | 1/3 | 1.333 | 75.0% |
| -250 | 2/5 | 1.400 | 71.4% |
| -200 | 1/2 | 1.500 | 66.7% |
| -175 | 4/7 | 1.571 | 63.6% |
| -150 | 2/3 | 1.667 | 60.0% |
| -140 | 5/7 | 1.714 | 58.3% |
| -130 | 10/13 | 1.769 | 56.5% |
| -125 | 4/5 | 1.800 | 55.6% |
| -120 | 5/6 | 1.833 | 54.5% |
| -115 | 20/23 | 1.870 | 53.5% |
| -110 | 10/11 | 1.909 | 52.4% |
| -105 | 20/21 | 1.952 | 51.2% |
| +100 | 1/1 | 2.000 | 50.0% |
| +105 | 21/20 | 2.050 | 48.8% |
| +110 | 11/10 | 2.100 | 47.6% |
| +115 | 23/20 | 2.150 | 46.5% |
| +120 | 6/5 | 2.200 | 45.5% |
| +125 | 5/4 | 2.250 | 44.4% |
| +130 | 13/10 | 2.300 | 43.5% |
| +140 | 7/5 | 2.400 | 41.7% |
| +150 | 3/2 | 2.500 | 40.0% |
| +175 | 7/4 | 2.750 | 36.4% |
| +200 | 2/1 | 3.000 | 33.3% |
| +250 | 5/2 | 3.500 | 28.6% |
| +300 | 3/1 | 4.000 | 25.0% |
| +400 | 4/1 | 5.000 | 20.0% |
| +500 | 5/1 | 6.000 | 16.7% |
| +1000 | 10/1 | 11.000 | 9.1% |
Worked examples in every odds format
- American favorite, -135: 135 / (135 + 100) = 57.4%.
- American underdog, +115: 100 / (115 + 100) = 46.5%.
- Decimal, 2.75: 1 / 2.75 = 36.4% (that is +175 in American odds).
- Fractional, 5/2: 2 / (5 + 2) = 28.6% (decimal 3.50, American +250).
- Removing the vig, -135 / +115 (shown to two decimals to match the calculator): 57.45% + 46.51% = 103.96%. Divide each side by the total: the fair probabilities are 55.26% and 44.74%, fair odds -124 / +124. The calculator’s Remove the vig tab returns the same numbers and a 3.81% hold (the 3.96% overround divided by the 103.96% total).
Break-even, fair and your probability: three different numbers
Implied probability is the break-even win rate the price you take requires. Fair (no-vig) probability is the market’s estimate once the margin is removed. Your probability is your own estimate. A bet has positive expected value only when your probability beats the break-even probability of the price you actually bet.
Example at -110 on both sides: break-even is 52.4% and fair is 50.0%. At 54% the bet is worth about $3.09 per $100 staked on average; at 51% it loses about $2.64 per $100, even though 51% is above the fair 50%.
Common implied probability mistakes
- Keeping the minus sign. For -150 use 150 / (150 + 100) = 60.0%, not -150 / -50.
- Forgetting that decimal odds include the stake. 2.50 means 1 / 2.50 = 40.0%, not 1 / 1.50.
- Rounding -110 to 52%. The exact break-even is 52.38%; small errors add up over many bets.
- Treating implied probability as the true chance. It includes the sportsbook margin, which is why both sides of a market add up to more than 100%.
- Comparing your estimate with the fair number, then betting the posted price. Check that your estimate also beats the break-even of the price you take.
More free PropsBot calculators: the parlay calculator for multi-leg tickets, the odds payout calculator for what a single bet pays, the odds converter to switch between American, decimal, fractional and percent odds, the no-vig fair odds calculator to strip the margin from a two-way line, the hedge calculator to size a hedge on a live ticket, and the 1X2 odds calculator for three-way soccer prices.
These are mathematical conversions of the prices you enter, not predictions. Must be 21+ (18+ in some jurisdictions) to bet. If you or someone you know has a gambling problem, call 1-800-GAMBLER.
