Kelly Criterion for Optimal Betting

Kelly Criterion Optimal Betting Calculator

Determine the optimal fraction of your bankroll to bet to maximize long-term growth.

Current Bankroll: The total amount of money you have available for betting.

Currency: Select the currency for your bankroll and bet amount. $ USD € EUR £ GBP A$ AUD C$ CAD ₹ INR Units

Kelly Multiplier: Bet a fraction of the full Kelly stake (e.g., 0.5 for Half Kelly, 1 for Full Kelly). Helps manage risk.

Bet Parameters

Win Probability (p): Your estimated probability of winning the bet. Enter as a decimal (e.g., 0.6 for 60%) or percentage (e.g., 60 for 60%). (Enter 0-1 or 0-100%)

Decimal Odds (D): The decimal odds offered by the bookmaker (e.g., 2.50). Must be greater than 1.

Optimal Bet Calculation

Kelly Fraction (f*):

Optimal Bet Amount:

Percentage of Bankroll to Bet:

Kelly Fraction vs. Win Probability (at current odds)

Understanding Kelly Criterion

• The Kelly Criterion calculates the optimal fraction of your bankroll to bet on an opportunity with positive expected value.
• f* = (bp - q) / b, where:
  • p = Probability of winning
  • q = Probability of losing (1 - p)
  • b = Net odds (Decimal Odds - 1)
• If f* ≤ 0, the bet doesn't offer a favorable risk/reward, and you should not bet.
• Using a Kelly Multiplier (e.g., 0.5 for Half Kelly) can reduce variance and risk, as full Kelly can be aggressive.
• Accuracy is key: The Kelly Criterion heavily relies on an accurate estimation of the win probability (p).