Expected Value Calculator

Category: Gambling
- May 08, 2025
| |

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.

What Is the Expected Value Calculator?

The Expected Value Calculator is a powerful Sportsbetting Calculator that helps bettors evaluate whether a wager is likely to be profitable in the long run. By combining your estimated chance of winning with the odds offered, it calculates the average return (positive or negative) you can expect per bet.

It supports multiple betting styles and formats, acting as both an Odds Calculator and a wagering analysis tool. Whether you're analyzing single bets or advanced outcomes with custom odds and stakes, this tool simplifies the Math behind smart betting decisions.

Basic Expected Value Formula:
EV = (Probability of Winning × Potential Profit) - (Probability of Losing × Stake)
Alternative Formula (based on your edge):
EV = (Your Assessed Probability − Implied Probability) × Stake ÷ Implied Probability

Why Use This Calculator?

This calculator is useful for:

  • Identifying bets with positive expected value (+EV), meaning they are profitable over time
  • Evaluating whether the odds probability offered by a bookmaker is in your favor
  • Comparing your own probability assessments with bookmaker odds
  • Converting between different betting odds formats like decimal, American, or fractional
  • Applying Kelly Criterion to calculate optimal bet sizing

It also functions as an odds conversion tool and betting ROI guide for smarter stake decisions.

How to Use the Calculator

  1. Select Calculation Method: Choose whether to use bookmaker odds only, your own assessed probability, or analyze multiple possible outcomes.
  2. Enter the Odds: Use the odds format converter to input odds as decimal, American, or fractional.
  3. Input Stake: Specify how much money you plan to bet.
  4. Add Probabilities: If you're using custom assessments, input your estimated probability of each outcome.
  5. Review Results: The tool shows expected profit/loss, return on Investment (ROI), edge percentage, and visual charts.
  6. Check Kelly Criterion: See how much you should wager to grow your bankroll optimally based on your edge.

Who Should Use It?

This is ideal for:

  • Sports bettors who want to make data-driven decisions
  • Users comparing different betting odds with their own predictions
  • People looking for a betting odds tool to evaluate stakes
  • Anyone interested in sports Statistics analysis or calculating expected returns

Key Features

  • Supports decimal, American, and fractional odds
  • Analyzes both single-outcome and multi-outcome bets
  • Calculates implied probability from odds
  • Provides edge, ROI, and EV breakdown
  • Includes a confidence range tool for probability uncertainty
  • Kelly Criterion betting guide built-in
  • Interactive EV chart for deeper insights

Frequently Asked Questions (FAQ)

What does a positive EV mean?
A positive expected value means that, over time, you’re likely to earn more than you lose with similar bets. It's a sign of a potentially profitable bet.



What is implied probability?
Implied probability is the likelihood of an outcome based on the odds. For example, decimal odds of 2.00 imply a 50% chance (1 ÷ 2.00).



How accurate is this calculator?
The math is accurate, but results depend on your probability estimates. The more precise your input, the more useful the analysis.



Can this help me convert betting odds?
Yes. It's also an odds format converter, helping you switch between decimal, American, and fractional odds easily.



Is this a guaranteed way to win?
No. This calculator helps with risk assessment and making informed choices, but betting always carries uncertainty.

Final Thoughts

The Expected Value Calculator is a practical Gambling odds tool for smarter, more disciplined betting. Whether you’re evaluating a straight bet or comparing multiple outcomes, this tool gives you clear numbers to base your decisions on.

Use it as a stake return calculator, odds probability tool, or Kelly strategy guide—and make each bet with more confidence and clarity.