Calculators
Kelly Criterion Calculator: Stake Size for Value Bets
The Kelly criterion turns your own estimate of a bet's chance into a stake size. Enter your bankroll, the odds and how likely you think the bet is to win and the calculator shows your edge and the suggested stake.
The Kelly Formula
Kelly stake = (chance × odds - 1) ÷ (odds - 1), as a share of your bankroll. Suppose you rate a team's chance of winning at 50% and the bookmaker offers 2.20. Your edge is 10%, and full Kelly says to stake 8.3% of your bankroll. With ₦50,000, that is about ₦4,167; half Kelly halves it to about ₦2,083.
| Your chance | Odds | Edge | Full Kelly | Half Kelly |
|---|---|---|---|---|
| 50% | 2.20 | 10% | 8.3% | 4.2% |
| 40% | 3.00 | 20% | 10.0% | 5.0% |
| 55% | 1.80 | -1% | No bet | No bet |
When the edge is zero or negative, Kelly tells you not to bet at all: the price is not good enough.
Why Most Punters Use Half or Quarter Kelly
Kelly is only as good as your chance estimate, and nobody estimates perfectly. Full Kelly also swings hard: a run of losses can cut your bankroll in half. Staking a half or a quarter of the Kelly amount keeps most of the growth with far smaller swings. It fits well with the rules on our bankroll management page.
If you cannot say why your chance is better than the bookmaker's, you do not have an edge. Use a flat stake instead.
Kelly Criterion FAQ
Where does my chance estimate come from?
From your own model or research. The bookmaker's implied chance is 1 divided by the odds; you need a better number than that.
Should I use Kelly on accas?
Rarely. The chance of a multi is hard to estimate, and small errors lead to large stakes.
Does Kelly guarantee a profit?
No. It sizes stakes for growth when you really have an edge; it cannot create one.