Kelly Criterion Calculator: Optimal Bet Size & Investment Strategy

Calculate Your Optimal Kelly Fraction

Enter your estimated probability of winning as a decimal (e.g., 0.55 for 55%).
Enter the net odds received. If you bet $1 and win $2 profit, b = 2.

Discover your optimal bet size or investment allocation with our free Kelly Criterion Calculator. This powerful mathematical formula helps you maximize long-term capital growth while managing risk. Apply the Kelly Criterion to sports betting, stock trading, or any scenario with quantifiable probabilities and odds.

Formula:

The Kelly Criterion formula calculates the optimal fraction (f) of your bankroll to wager, based on your estimated probability of winning (p) and the odds you're offered (b). Let q be the probability of losing, where q = 1 - p.

Formula:

f = p - (q / b)

Where:

  • f = The optimal fraction of your bankroll to bet (as a decimal)
  • p = Your perceived probability of winning (as a decimal, e.g., 0.55 for 55%)
  • q = Your perceived probability of losing (1 - p)
  • b = The net odds received (e.g., if odds are 2:1, b = 2)

A positive 'f' indicates an advantage, while a negative 'f' suggests you shouldn't bet.

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