Kelly Criterion Roulette Strategy
Kelly Criterion is the optimal bet sizing formula - for positive-expected-value bets. Roulette has negative EV, so Kelly always recommends bet size zero. There is no Kelly roulette strategy.
What Kelly Criterion is
A formula for optimal bet sizing when you have an edge. Kelly maximises long-run bankroll growth rate by sizing each bet as a percentage of current bankroll based on the edge and odds.
Standard form: f = (bp − q) / b, where b is the net odds, p is win probability, q is loss probability.
Why Kelly breaks on roulette
Kelly requires positive expected value. Roulette has negative EV on every standard bet.
Plug roulette numbers in: red on European, b=1, p=0.4865, q=0.5135. f = (1 × 0.4865 − 0.5135) / 1 = −0.027.
Kelly recommends betting −2.7% of bankroll - meaning take the bet for the casino, not the player. Since you cannot do that, Kelly says bet zero.
Why no positive-EV roulette bet exists
Every standard payout is below true odds. The gap is the house edge. No betting pattern creates a positive-EV combination from negative-EV components.
Honest conclusion
There is no Kelly roulette strategy. Anyone selling one is either misunderstanding the formula or being dishonest.
Kelly applies to advantage play - card counting, biased wheels, dealer signature - where the player has identified a real edge. It does not apply to betting systems.