Implied Probability Calculator

Category: Gambling
- June 23, 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 handy tool for bettors. It helps you calculate the implied probability of an event based on betting odds. By doing so, you can see how these odds align with your own assessment of the event's true probability. This can be a crucial step in finding value bets and making informed betting decisions.

How to Use the Calculator

Using this calculator is straightforward. You can enter the odds in several formats, including decimal, fractional, and American. Additionally, you can input your estimated probability of the outcome and the amount you plan to stake. The calculator then works out important figures like implied probability, expected value, and more, so you get a complete picture of your betting situation.

Understanding Implied Probability

Implied probability reflects how likely an event is, according to the odds set by bookmakers. Here’s how to calculate it from different types of odds:

  • 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)

Identifying Value Bets

A value bet occurs when your estimated probability is higher than the bookmaker's implied probability. The difference between these probabilities is known as your edge. This edge is significant because it shows where you may find betting opportunities that can yield positive returns over time. Always look for these differences when evaluating your bets.

Calculating Expected Value (EV)

Expected Value (EV) is a measure of how much you can expect to win or lose per unit wagered over the long run. The formula for EV is simple:

  • EV = (Probability of winning × Potential profit) - (Probability of losing × Stake)

This means that positive EV bets can lead to profitability over time, while negative EV bets can deplete your bankroll.

The Role of Bookmaker Margin

Bookmakers typically add a margin to their odds, which causes the total implied probability of all possible outcomes to exceed 100%. This margin, often called vig or juice, can range from 2% to 10%. To find the true fair odds, it’s essential to consider this margin when assessing the implied probabilities.

Visualising Your Bets

The calculator also provides a visual analysis of the probabilities involved. A chart displays the various probabilities, helping you to see at a glance how your estimated probability stacks up against the bookmaker’s implied probability. This visual aid can be a powerful tool in your betting strategy, making complex data easier to interpret.

Why This Calculator Matters

The Implied Probability Calculator is crucial for anyone looking to make informed betting decisions. By understanding both implied and true probabilities, you can identify value bets and enhance your overall betting strategy. Remember, this tool is for educational purposes, so always consider Other factors when placing your bets.