Kelly Criterion Bet Calculator: Optimizing Bet Sizes

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On this page you'll find a Kelly Criterion Bet Calculator. Enter your assumptions on

  • Probability of winning
  • Odds and payouts
  • Your current bankroll
  • Any adjustments you want to make to be conservative

We automatically calculate your ideal bet size with the Kelly Criterion and your assumptions.

The Kelly Criterion Bet Calculator

Practical Application of the Kelly Criterion To Betting Strategies

The Kelly Criterion is a formula to determine the proper size of a bet with known odds and a definite payout. With hand waving and basic math you can also use it to help guide your investment decisions.

It's most useful to determine the size of a position you should take.

Using the Kelly Calculator

The Kelly Criterion bet calculator above comes pre-filled with the simplest example: a game of coin flipping stacked in your favor.

  • The casino is willing to pay 2 to 1 on any bet you make.
  • Your odds of winning any one flip are 50/50.
  • Therefore, your probability is .5... 50%.
  • Your 'odds offered' are '2 to 1' (so enter 2).
  • You have $1,000 with you.

Hit calculate, and see that you should definitely take the bet. Your optimal bet size is 25% of your bankroll.

(Now, find a casino stupid enough to offer those odds!)

Of course, you can see practical the practical value of Kelly betting when it comes to things with discrete results and obvious probabilities - say pot odds in a poker hand. Your mileage may vary.

What do you think about simple Kelly betting? Even though it is designed to never let you go bankrupt, Kelly still allows wild volatility swings.

Do you prefer another strategy? Perhaps half or quarter Kelly methods?



PK started DQYDJ in 2009 to research and discuss finance and investing and help answer financial questions. He's expanded DQYDJ to build visualizations, calculators, and interactive tools.

PK lives in New Hampshire with his wife, kids, and dog.

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