Implied Probability Calculator

An implied probability calculator converts betting odds into the win probability they imply — the break-even chance a bet must clear to be profitable at that price.

Enter any American or decimal price to see the implied probability it represents, or enter a probability to get the equivalent odds. The calculator also shows the decimal, fractional, and payout equivalents so you can read any line at a glance.

Odds ↔ implied probability

Enter a price or a probability

e.g. -110 or +150

Common prices

Implied probability

52.38%

Break-even win rate to profit at this price

American odds

-110

Decimal odds

1.91

Fractional

10/11

Payout per $100

$190.91

This is the raw implied probability — it still includes the book's vig. Devig the market to get the fair, true probability.

What is implied probability?

Implied probability is the win probability baked into a set of odds. Every price — whether it's American (-110), decimal (1.91), or fractional (10/11) — corresponds to a percentage chance the outcome must hit for the bet to break even. It's the single most useful number in betting because it converts every odds format onto the same scale: probability.

The formulas

Positive American odds: probability = 100 / (odds + 100). So +150 → 100 / 250 = 40%.
Negative American odds: probability = |odds| / (|odds| + 100). So -110 → 110 / 210 = 52.38%.
Decimal odds: probability = 1 / decimal. So 1.91 → 1 / 1.91 = 52.36%.

To go the other way — probability back to odds — invert the math: decimal odds = 1 / probability, and American odds follow from there. This calculator does both directions automatically.

Raw vs. fair (no-vig) probability

The implied probability of a single price is the raw probability — it still includes the sportsbook's vig, so it slightly overstates the true chance. Add up both sides of a market and you'll get more than 100%; the excess is the margin. To get the fair probability with the vig removed, devig the market. That's the number you compare against to find +EV bets.

When to use this calculator

Use it any time you want to translate a price into a probability — to sanity-check whether a line matches your own estimate, to compare odds across formats, or to figure out the break-even win rate a bet needs. If you think a team wins 60% of the time and the price implies only 50%, that's a signal worth a closer look.

Remember the implied probability of a single price includes vig. To strip it out and get the fair price, use the devig calculator; to measure the margin itself, use the vig calculator.

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Frequently asked questions

What is implied probability in betting?

Implied probability is the win probability that a set of odds represents — the break-even chance an outcome must hit for the bet to be profitable at that price. It puts American, decimal, and fractional odds onto a single comparable scale.

How do you convert odds to implied probability?

For positive American odds: 100 / (odds + 100). For negative American odds: |odds| / (|odds| + 100). For decimal odds: 1 / decimal. Example: -110 → 110 / 210 = 52.38%; +150 → 100 / 250 = 40%; decimal 1.91 → 52.36%.

How do you convert a probability back to odds?

Decimal odds equal 1 / probability. From there, if the probability is 50% or higher the American odds are negative (favorite); below 50% they are positive (underdog). This calculator converts in both directions — enter a price to get a probability, or enter a probability to get the odds.

Is implied probability the same as the true probability?

No. The implied probability of a single price includes the sportsbook's vig, so it slightly overstates the real chance. Add both sides of a market and the total exceeds 100% — that excess is the margin. Devig the market to get the fair, true probability used to find +EV bets.

What is break-even win rate?

It is the implied probability of the price you are betting — the percentage of bets you must win, long term, just to break even at those odds. At -110 you need to win about 52.38% of the time; at +150 you only need 40%. Beating the break-even rate is how you turn a profit.

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