CALCULATOR KELLY

Calculate the optimal stake using the Kelly Criterion. The mathematical formula that maximizes your bankroll growth in the long run.

Bet data

Bankroll (€)

Decimal odds

Confidence (1-10)

6/10 — Estimated probability: 60%

WHAT IS THE KELLY CRITERION

The Kelly Criterion is a mathematical formula that determines the optimal percentage of your bankroll to bet. It was developed by John L. Kelly Jr. in 1956 to optimize the long-term capital growth rate.

THE FORMULA

f* = (p × b - q) / b

f* = optimal bankroll fraction
p = probability of winning (your estimate)
q = probability of losing (1 - p)
b = decimal odds - 1 (net profit per unit staked)

WHY HALF KELLY

In practice, most professional bettors use Half Kelly (50% of the calculated value). Reasons:

Dramatically reduces variance without sacrificing much growth
Compensates for errors in probability estimation
Maximum drawdown is reduced by approximately half

StakeMaster applies Half Kelly by default and caps the stake at 10% of the bankroll as an additional safety measure.

WHEN NOT TO USE KELLY

If f* is negative, the bet has no positive expected value — do not bet
If your probability estimate is unreliable, Kelly amplifies errors
For parlays or accumulators, Kelly does not apply directly

KELLY BUILT INTO YOUR DASHBOARD

In StakeMaster you can calculate Kelly directly when creating each bet. Record, analyze and improve.

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