Implied Probability Calculator
Convert betting odds to implied probability and identify value bets by comparing with your own probability estimate.
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How to use this calculator
Implied probability is the market's estimate of an outcome's chance of happening, expressed as a percentage. The tool also shows the gap between that figure and a probability you type in, and the average result per stake if your estimate were correct.
- 1
Select the odds format your sportsbook uses.
- 2
Enter the odds for the selection you are checking.
- 3
Enter your own estimate of the outcome's probability.
- 4
Read the implied probability, the gap to your estimate, and the average result per stake if your estimate were correct.
Frequently asked questions
What formula does this tool use?
Decimal odds d give 1 ÷ d. American +N gives 100 ÷ (N + 100). American −N gives N ÷ (N + 100). Each is multiplied by 100 and shown to one decimal. Decimal 2.00 and American +100 both return 50.0%, and −110 returns 52.4%.
How do I enter negative American odds?
Choose “American Negative” and type the size without the sign, so 200 means −200. A leading minus (−200) or plus sign is also accepted and the tool uses the size either way. American odds must have a size of 100 or more.
What does the “expected result” line mean?
It is stake × (your probability × (decimal − 1) − (1 − your probability)), the average outcome per stake if your estimate were exactly right. At decimal 2.00, a 55% estimate and a stake of $100 it is $10.00. The line is only as reliable as the estimate you type, and the tool cannot tell you whether the estimate is sound.
Why does the line compare my estimate with the implied probability?
To show the gap in percentage points. A 55% estimate against a 50.0% implied probability is +5.0 points. A 35% estimate against 40.0% is −5.0 points. The comparison is arithmetic only. It does not say a wager will win, and probability estimates are uncertain.
Does the implied probability include the bookmaker’s margin?
Yes, whatever margin is in the price is included, because the tool converts one price at a time. It does not compute overround. Two sides each priced at −110 both show 52.4%, which together add up to more than 100%; the tool does not display that total.
What happens with bad input?
A decimal price of 1.00 or below, an American size under 100, or text that is not a number returns a message rather than a result. A decimal comma such as 2,50 is accepted. Your probability is held between 0 and 100, and a stake of 0, which is also what a cleared box becomes, is treated as 100.
Is this betting advice?
No. The tool converts a price into a probability and does some arithmetic with an estimate you supply. Betting carries a risk of losing the stake, and the legal position depends on where you live.
Implied probability calculator for decimal and American odds
What a price implies
Every betting price can be read as a probability: the chance at which the stake and the payout would balance. A price of decimal 4.00 pays four times the stake, so it breaks even at a one-in-four chance, 25%. This calculator does that conversion for decimal and American odds, and then lets you compare the result with a probability of your own to see the difference in percentage points.
| Format | Implied probability | Example input | Result |
|---|---|---|---|
| Decimal d | 1 ÷ d | 2.00 | 50.0% |
| American +N | 100 ÷ (N + 100) | +150 | 40.0% |
| American −N | N ÷ (N + 100) | 200 (as −200) | 66.7% |
| American −N | N ÷ (N + 100) | −110 | 52.4% |
Worked examples with an estimate
At decimal 2.00 the implied probability is 50.0%. If you entered 55% as your own estimate, the difference is +5.0 points and the average outcome per $100 staked would be $10.00 if the estimate were right. At +150 (decimal 2.50) the implied probability is 40.0%, and an estimate of 35% is 5.0 points lower, an average of −$12.50 per $100. At −200 the implied probability is 66.7%; an estimate of 60% gives −6.7 points and −$10.00.
| Price | Implied | Your estimate | Difference | Average per $100 |
|---|---|---|---|---|
| 2.00 (decimal) | 50.0% | 55% | +5.0 pts | $10.00 |
| +150 | 40.0% | 35% | −5.0 pts | −$12.50 |
| −200 | 66.7% | 60% | −6.7 pts | −$10.00 |
| −110 | 52.4% | 50% | −2.4 pts | −$4.55 |
Why the estimate matters most
The comparison line is arithmetic on two inputs. One of them, the price, is on the screen. The other, your probability, is an opinion that carries all the uncertainty. A change of a few points in the estimate swings the average outcome from positive to negative, as the table shows. Read the figure as a sensitivity test on that estimate, not as a forecast.
One price at a time
The tool reads a single price. In a real market each outcome has its own price, and the implied probabilities across all outcomes typically add up to more than 100%, because the operator builds a margin into the prices. This calculator does not add the outcomes together, so it cannot show the size of that margin.
Limits and risk
The calculator reads one price and one estimate at a time. No allowance is made for fees, taxes, voided stakes or partial returns. Gambling involves a risk of losing money, and it is legal only in some places, so check the rules that apply to you.
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →