Kelly calculator: how much to stake for your edge
Enter the probability you give the outcome, the odds and your bankroll. You see whether there is an edge and what share of your bankroll the Kelly criterion suggests.
How it works
Kelly = (probability × odds − 1) ÷ (odds − 1). At 50% and odds of 2.20 that is 8.3% of the bankroll.
Full Kelly maximises long-run bankroll growth only if your probability is exact. It never is, and full Kelly on an optimistic estimate leads to brutal drawdowns. That is why most people use a fraction: a quarter or a half.
Where the probability comes from
That is the real work. You can start from the market's no-margin probability (fair odds calculator) or from a model: MatchScan calculates one for any match in 31 leagues in the analyser.
Frequently asked questions
What is the Kelly criterion? A formula for what share of your bankroll to stake given your edge and the odds, to grow the bankroll as fast as possible in the long run.
Why use fractional Kelly? Because your probability has error. Half or quarter Kelly grows a little slower but with far smaller drawdowns.
What if Kelly comes out negative? Then you have no edge at those odds: don't bet.
Gamble responsibly · begambleaware.org