Question 1

What is the Kelly Criterion in poker bankroll management?

Accepted Answer

The Kelly Criterion determines the optimal fraction of wealth to risk on positive-expectation wagers to maximize the long-term geometric growth rate of capital while avoiding gambler's ruin.

Question 2

Why do poker professionals use Fractional Kelly (Half or Quarter)?

Accepted Answer

Full Kelly experiences devastating drawdowns exceeding 50% and assumes perfectly known win rates and standard deviation. Half Kelly sacrifices only 25% of growth rate while cutting variance in half, providing an essential safety buffer against downswings and estimation errors.

Question 3

How is Risk of Ruin (RoR) calculated in cash games?

Accepted Answer

Under a continuous Brownian motion model with drift μ and variance σ², the analytical Risk of Ruin with bankroll B is given by R = exp(-2μB / σ²).

Question 4

What standard deviation should I use?

Accepted Answer

Standard deviation depends on game format: 9-max full ring is typically 65-80 bb/100, 6-max is 85-115 bb/100, and heads-up or PLO can reach 130-180 bb/100.

Question 5

How many buy-ins do I need for a 1% Risk of Ruin?

Accepted Answer

For a 5 bb/100 win rate and 85 bb/100 standard deviation, a 1% RoR requires approximately 33 to 35 buy-ins. At a lower win rate of 2 bb/100, the requirement jumps to over 83 buy-ins.

Kelly Criterion Poker Bankroll Calculator

Bankroll & Performance Parameters

Quantitative Risk & Sizing Profile

Required Bankroll by Ruin Probability Threshold

Risk of Ruin vs Bankroll Depth (Analytical Curve)