Expected Value Calculator

Category: Gambling
- June 26, 2025
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Calculate the expected value (EV) of your sports bets to make more informed wagering decisions. This tool helps you determine whether a bet has positive expected value (profitable long-term) or negative expected value (unprofitable long-term).

Bet Information

Choose how you want to calculate your edge
The odds offered by the bookmaker
£
How much you plan to wager
%
Estimated bookmaker's commission (typical: 2-10%)

Understanding Expected Value in Betting

Expected Value (EV) is a mathematical concept used to determine the average outcome of a bet over the long run. A positive expected value (+EV) indicates a profitable bet, while a negative expected value (-EV) suggests an unprofitable one.

How Expected Value Is Calculated

The basic formula for calculating the expected value of a bet is:

EV = (Probability of Winning × Potential Profit) - (Probability of Losing × Stake)

Alternatively, it can be expressed as:

EV = (Your Assessed Probability - Implied Probability) × Stake / Implied Probability

For multiple outcomes, the EV is the sum of the probability of each outcome multiplied by its respective profit or loss.

Implied Probability vs. True Probability
  • Implied Probability: The probability reflected in the bookmaker's odds. For decimal odds, it's calculated as: 1 ÷ Decimal Odds.
  • True (Assessed) Probability: Your assessment of how likely an outcome actually is, based on your analysis.
  • Edge: The difference between your assessed probability and the implied probability. A positive edge means you believe an outcome is more likely than the odds suggest.
Kelly Criterion For Optimal Bet Sizing

The Kelly Criterion is a formula that determines the optimal bet size to maximize long-term wealth growth. The formula is:

Kelly % = (bp - q) ÷ b

Where:

  • b = the decimal odds - 1 (net odds received on the bet)
  • p = the probability of winning
  • q = the probability of losing (1 - p)

Many bettors use a fractional Kelly approach (half or quarter Kelly) to reduce variance while maintaining growth.

Practical Considerations
  • Bookmaker Margin: Also known as vigorish, juice, or overround - the profit margin built into the odds.
  • Probability Assessment: The accuracy of your probability estimates directly impacts EV calculations.
  • Confidence Levels: Consider the uncertainty in your probability estimates.
  • Long-Term Thinking: EV is about long-term expectation, not individual results.
  • Bankroll Management: Even positive EV bets can lead to bankruptcy if bet sizing isn't appropriate.

Disclaimer: This calculator provides mathematical calculations for informational purposes only. Sports betting involves risk, and there's never a guaranteed outcome. This tool helps identify potentially valuable bets based on the information you provide, but the accuracy depends on your probability assessments. Always gamble responsibly and within your means.

Understanding the Expected Value Calculator

The Expected Value Calculator is a handy tool designed for Sports bettors who want to make informed decisions. It calculates the expected value (EV) of your bets, helping you figure out if a wager is likely to be profitable in the long run. With this calculator, you can assess your betting strategies and determine the best courses of action based on the odds and your own probability assessments.

How to Use the Calculator

Using the Expected Value Calculator is simple, even for beginners. You start by selecting a calculation method, either using implied probability, your own assessed probability, or an advanced method for multiple outcomes. Then, you enter the odds format, bookmaker odds, and your stake amount. With these inputs, the calculator provides insights into the potential value of your bets.

The Importance of Implied and True Probability

Understanding implied and true probability is vital for getting the most out of the Expected Value Calculator. Here's a quick breakdown:

  • Implied Probability: This is derived from the bookmaker's odds and shows the likelihood of an event occurring.
  • True Probability: This is your own assessment of how likely you think an event will happen based on your research.
  • Edge: This is the difference between your assessed probability and the implied probability, indicating your advantage if positive.

Calculating Your Edge in Betting

The calculator helps you calculate your edge, which is critical for successful betting. A positive edge suggests that the outcome is more likely than the odds imply. By using your assessed probability against the bookmaker's implied probability, you can see if your bet has a good chance of paying off. The calculator will show you the edge percentage, allowing you to compare various betting options.

Analyse Multiple Outcomes with Ease

If you're dealing with multiple outcomes, the Expected Value Calculator simplifies the process. You can input various outcomes along with their odds and your assessed probabilities for each. The calculator will analyse all outcomes to provide an overall expected value. This feature is particularly useful when betting on events with more than two possible results.

Understanding Expected Value Analysis

The analysis provided by the calculator gives insights into the expected value from your bets. For instance, a positive expected value suggests that there is potential for profit, while a negative expected value indicates a probable loss. This analysis includes additional details such as implied probability, your assessed probability, and return on Investment, making it easier to make informed decisions.

Using the Kelly Criterion for Bet Sizing

The Expected Value Calculator also incorporates the Kelly Criterion, which helps you determine the optimal bet size based on your bankroll. This method aims to maximise your long-term growth while reducing the risk of losing your entire stake. You can choose between full, half, or quarter Kelly stakes to match your risk tolerance. This way, you can make smarter betting choices that align with your Financial goals.

Making Informed Betting Decisions

By using the Expected Value Calculator, you not only get a straightforward analysis of your bets but also a deeper understanding of betting strategies. The calculator encourages responsible Gambling by helping you evaluate your options based on calculated risk and potential return. This empowers you to make more informed betting decisions and enhances your overall betting experience.