Probability
Implied Odds and Probability Calculator
Use this implied odds calculator to convert a betting price to a percentage, a probability to odds, or independent event estimates to a combined parlay probability.
Odds to implied probability and back
Turn odds into an implied probability, or a probability into the matching American and decimal odds.
Implied probability
40%
Odds of +150 imply a 40% chance, before removing any vig.
- American odds
- +150
- Decimal odds
- 2.50
- Fractional odds
- 3/2
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Several independent events
Enter your own probability estimates for three events. If they are independent, the chance that all of them happen is the product of the probabilities.
All three happen
12%
50% × 40% × 60% = 12%
- Equivalent American odds
- +733
- Equivalent decimal odds
- 8.33
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Dependent events
If the events affect each other – two outcomes in the same game, for example – the simple product does not apply.
What implied probability means
Implied probability is 1 divided by the decimal odds: +150 (2.50) implies 1 / 2.50 = 40%. For negative American odds it is |odds| / (|odds| + 100), so −110 implies 110 / 210 = 52.38%. This is not the real chance of the result. Sportsbook prices include a margin, so the implied probabilities in a market usually add up to more than 100%.
To remove that margin, use the no-vig calculator. It scales the probabilities so they add up to exactly 100%.
| American | Decimal | Implied probability |
|---|---|---|
| -400 | 1.25 | 80% |
| -200 | 1.50 | 66.67% |
| -110 | 1.91 | 52.38% |
| +100 | 2.00 | 50% |
| +150 | 2.50 | 40% |
| +300 | 4.00 | 25% |
| +900 | 10.00 | 10% |
Parlay probability calculator for independent events
Use the independent-events block above to multiply your own estimated chances. Three independent legs at 50%, 60% and 70% have an all-win probability of 0.50 × 0.60 × 0.70 = 21%. The corresponding fair decimal odds are 1 ÷ 0.21, approximately 4.7619, before margin.
An implied odds calculator reads the probability built into a price. That is different from estimating the actual probability: three +100 prices imply 50% each, but their true chances are not verified. Correlated same-game selections cannot be treated as independent. The tool does not convert an NFL point spread into a win probability; that requires a calibrated score-distribution model.
For a percentage-to-odds conversion, enter 40% in the conversion block: that corresponds to decimal 2.50 or American +150. To calculate dollar winnings instead, use the parlay payout calculator.
Why 0% and 100% are not odds
A price can never imply exactly 0% or 100%: 0% would need infinitely long odds, and 100% would mean decimal odds of 1.00, where you only get your stake back. That is why the conversion accepts values strictly between 0 and 100. In the independent-events block, 0% and 100% are allowed because they are ordinary mathematical probabilities.