Implied Probability Calculator: Convert Odds to Percent
Implied probability is the chance of winning that a set of odds corresponds to: 1 divided by the decimal odds. At -110 it is 52.38%, which is also the share of bets you must win to break even. It includes the sportsbook's margin, so it overstates the true chance.
Key facts
- Implied probability from decimal odds is 1 ÷ decimal odds (Wikipedia, Implied probability).
- For negative American odds, probability = |odds| ÷ (|odds| + 100); for positive odds, 100 ÷ (odds + 100).
- At -110 the break-even win rate is 52.38%.
Odds are a price, and every price implies a probability. Seeing that number is the first step to knowing whether a bet is worth taking. Enter your own estimate as well and the calculator shows the gap and the expected result per $100. It runs in your browser, sends nothing anywhere and forgets your numbers when you close the page.
Implied probability calculator
Turn on JavaScript to use the calculator. The worked example below shows the same math by hand.
What you enter and what you get
You enter
- Odds: American, decimal or fractional.
- Your estimated win chance (%) (optional): Adds the gap and the expected result.
You get
- You need to win
- Implied probability (break-even win rate)
- Profit per $100 if it wins
- Loss per $100 if it loses
- Your estimated win chance
- Gap vs the odds
- Fair odds at your estimate
- Expected result per $100
How the calculator works
- Convert the odds to decimal.
- Divide 1 by the decimal odds. That is the implied probability.
- That same figure is the break-even win rate.
- If you add your own estimate, subtract the two to see the gap, and price the bet at your estimate.
A worked example
Odds of +150, with your own estimate set at 45%.
| Item | Result |
|---|---|
| You need to win | 40% |
| Implied probability (break-even win rate) | 40% |
| Profit per $100 if it wins | $150 |
| Loss per $100 if it loses | -$100 |
| Your estimated win chance | 45% |
| Gap vs the odds | 5 points |
| Fair odds at your estimate | +122 (decimal 2.22) |
| Expected result per $100 | $12.5 |
What the calculator leaves out
- Implied probability includes the margin, so a two-way market sums to more than 100%.
- It doesn't know the true chance. Your estimate does the work.
- Odds from different sites can imply different chances for the same event.
How we checked it
Before it went on the page we checked it against values worked by hand: +150 has to come out at exactly 40%, and an empty or non-numeric entry has to ask for a number instead of showing a result. The calculator is also run against thousands of odd entries such as blanks, zeros and huge numbers, so a bad entry shows a plain prompt and never a wrong number. The worked example above comes from the same code the calculator runs.
At a sweepstakes sportsbook
Odds shown by a sweepstakes sportsbook imply a probability the same way. What differs is what a win is worth: it's paid in the site's coins and subject to its redemption rules, which are worth reading first. See where sweepstakes sites can operate.
Betting math is not betting advice. Only play with money you can afford to lose, and if gambling stops being fun, call or text 1-800-GAMBLER.
Frequently asked questions
Why does -110 imply 52.38% and not 50%?
The extra 2.38% pays the sportsbook's margin. You must win 52.38% of such bets to break even.
How do I convert plus odds?
Probability = 100 ÷ (odds + 100). At +150 that is 100 ÷ 250, or 40%.
Is implied probability the true chance?
No. It is the price with margin built in. Removing the margin gets closer, as in our no-vig calculator.
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- Implied probability, Wikipedia (read 2026-10-05)
- Odds, Wikipedia (read 2026-10-05)
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