Implied Probability Calculator

Category: Gambling
- November 21, 2025
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Calculate the implied probability from betting odds and compare true probabilities to find value bets. This calculator helps bettors identify opportunities where the bookmaker's implied probability differs from your estimated true probability.

Enter Odds & Probability

Enter odds in your preferred format
%
Your assessment of the true probability
£
Amount you plan to bet
%
Typically ranges from 2% to 10%

Understanding Implied Probability

Implied probability represents the probability of an outcome as reflected in the odds. It's how bookmakers express their assessment of the likelihood of an event.

How to Calculate Implied Probability
  • For Decimal odds: Implied Probability = 1 / Decimal Odds
  • For Fractional odds: Implied Probability = Denominator / (Denominator + Numerator)
  • For American odds:
    • If positive (+): Implied Probability = 100 / (Odds + 100)
    • If negative (-): Implied Probability = |Odds| / (|Odds| + 100)
Finding Value in Betting

A value bet occurs when your estimated probability of an outcome is higher than the bookmaker's implied probability. The difference between these probabilities is your edge.

Expected Value (EV) is a mathematical concept that tells you how much you can expect to win or lose per unit wagered over the long run. Positive EV bets are profitable over time.

Bookmaker Margin (Vig/Juice)

Bookmakers build a profit margin into their odds, making the total implied probability of all possible outcomes exceed 100%. This margin (also called vigorish or juice) typically ranges from 2% to 10%.

To find the true fair odds without margin, you need to remove this overround from the implied probability.

Disclaimer: This calculator provides theoretical mathematical analysis based on probability theory. Actual betting outcomes depend on numerous unpredictable factors. This tool is for informational purposes only and should not be the sole basis for betting decisions.

What is the Implied Probability Calculator?

The Implied Probability Calculator is a helpful tool for bettors. It allows you to calculate the implied probability from different betting odds. By using this calculator, you can assess whether a bet offers real value based on your own estimated probabilities compared to those set by bookmakers.

How to Use the Calculator

Using the Implied Probability Calculator is straightforward. Just enter odds in your preferred format, such as decimal or fractional. Then, input your estimated probability and stake amount. There’s even an option to include the bookmaker’s margin, which affects the odds you see. This makes it easier to analyse potential betting opportunities.

The Importance of Implied Probability

Implied probability reflects how likely an outcome is according to the odds given by bookmakers. Understanding this helps you gauge how bookies view the event. Here’s what to keep in mind:

  • It’s calculated differently based on the odds format.
  • It can help you find value bets, which are bets where your perceived chance of winning is higher than the bookmaker's odds suggest.
  • It aids in identifying bets that could be profitable long-term.

Calculating Implied Probability

Implied probability can be calculated based on the type of odds you’re using. Here’s a simple breakdown:

  • Decimal odds: Implied Probability = 1 / Decimal Odds
  • Fractional odds: Implied Probability = Denominator / (Denominator + Numerator)
  • American odds:
    • If positive (+): Implied Probability = 100 / (Odds + 100)
    • If negative (-): Implied Probability = |Odds| / (|Odds| + 100)

Understanding Your Edge and Expected Value

When placing bets, it's key to understand your edge and expected value (EV). The edge is the difference between your estimated probability and the implied probability. Expected value tells you how much you can expect to win or lose over time:

  • A positive EV means a bet may be profitable.
  • A negative EV indicates a potential loss over time.

The Role of Bookmaker Margin

Bookmakers include a margin in their odds to ensure they make a profit. This margin, known as vig or juice, usually ranges from 2% to 10%. It causes the total implied probability across all outcomes to exceed 100%. Understanding this helps you adjust your calculations to find the true fair odds.

What You Can Learn from the Results

The results from the Implied Probability Calculator give you valuable insights. You’ll see both the implied and your estimated probabilities, plus the edge and expected value based on your stake. This data helps you assess whether a bet is worth placing or if it’s simply a neutral wager.

Final Thoughts on Betting Smart

The Implied Probability Calculator is a great asset for anyone looking to improve their betting strategy. By understanding the odds, calculating implied probability, and assessing value, you can make more informed decisions. This tool makes it easier to navigate the betting landscape, increasing your chances of success.