Kelly Criterion Calculator

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This online Kelly criterion calculator determines a recommended stake based on the prevailing odds and your estimated probability that the selection will win.

All of the major odds formats are supported. This calculator also supports markets where a push/refund is possible as well as lay betting on a betting exchange such as Betfair. Fractional Kelly betting is also supported.

The Kelly criterion is formula that calculates the proportion of your balance to wager on a particular gamble. Learn more about the Kelly criterion.

Input Guides

Note that some of these variables only apply when you switch to the betting exchange version of the calculator.

  • Betting account balance
    The Kelly criterion calculates the portion of your funds to place on a wager. The calculator will multiply this number by the account balance you specify to yield a recommended stake. Do not include any currency symbols.
  • Minimum accepted stake
    Input the minimum accepted stake that your betting exchange permits. E.g. Betfair has a minimum stake amount of $5.00 for Australian currency accounts, in which case you would enter enter 5.00. Do not include any currency symbols.
  • Exchange commission
    If you are using a betting exchange that charges commissions on winning bets, input the commission here (e.g. input 0.05 if the commission is 5%). Do not include the % symbol. Note that this calculator does not support the Matchbook commission structure.
  • Fractional Kelly betting
    The recommended Kelly criterion stake will be multiplied by this value. For standard Kelly betting, set the fractional Kelly betting value to 1.00. If you want to be more conservative than the Kelly criterion, enter a value less than 1 (e.g. input 0.5 if you want to wager 50% of the stake recommended by the Kelly criterion).
  • Odds
    The odds offered by the bookmaker or exchange. Users of the betting exchange versions of the calculator can enter the back and/or the lay odds. Make sure the odds format is consistent with the one chosen in the Settings field.
  • Probability of winning
    This is your estimated probability that the selection will win. The Kelly criterion uses this value to calculate a recommended stake. It should be a value between 0 and 1 (e.g. input 0.5 if your believe the selection has a 50% chance of winning). Do not include the % symbol.
  • Probability of refund/push
    If you are considering a line bet such as -3.0 or any other market with a distinct possibility of receiving a refund, enter your estimated probability of a push/refund into this field. It should be between 0 and 1 (e.g. input 0.03 if you believe the bet has a 3% chance of being refunded). Do not include the % symbol. Note that the the probability of winning and the probability of a refund should not sum to more than 1.

Kelly Criterion Calculator

If you are unsure how to use this calculator, leave the fields at their default values and click on “Calculate Stake” to see how it works.

Calculator version:

Select whether you with to use the bookmaker or betting exchange (e.g. Betfair) version of the calculator. The bookmaker version is shown by default.


Bookmaker Kelly Criterion Calculator

Fields marked in bold are required.

Odds format:
Betting account balance ($):
Fractional Kelly betting:
Wager details
Bookmaker odds
Probability of winning:
Probability of refund/push:


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