The Kelly Criterion Applied to Crash Auto-Cashout
Kelly tells you the EV-optimal fraction of your bankroll to bet. For Crash, it tells you to bet zero. The honest answer.
Kelly in one formula
f* = (bp - q) / b where b is the payout per dollar won, p is the win probability, q is 1 minus p. f* is the fraction of your bankroll to stake per bet.
Positive f*: bet that fraction. Negative f*: don't bet. Zero f*: don't bet. The formula doesn't moralize — it tells you the size that maximizes long-run logarithmic bankroll growth, and on losing bets, that size is zero.
The Kelly criterion doesn't lie. When it says zero, the game has no positive-EV strategy. Believing otherwise is the gambler talking.
Applied to Crash
At a 2x cashout target, b = 1 and the win probability p is whatever the house-banked odds make it. Because Crash is negative-EV, bp comes out below q, so f* lands below zero. A negative f* means: don't bet.
At a 10x target, b = 9 and p shrinks roughly in proportion, so bp - q stays negative. Still below zero. Same answer.
Every cashout target on Crash produces negative Kelly. Because every cashout target has the same long-run EV, the result is structural: when the underlying game loses money long-run, no bet size on top of it makes money.
When Kelly turns positive
Rakeback and promos only change the answer when the verified overlay is larger than the underlying house-banked loss. Without that, Kelly stays at zero no matter how low the cashout target is.
Even when an external bonus creates a real positive overlay, quarter-Kelly usually calls for a fraction of the headline stake. Stacking bonuses on top of low-edge games is the only honest path to positive Kelly numbers, and even then the returns are grinder-grade.
Why quarter-Kelly
Full Kelly maximizes growth rate but with massive volatility. Full-Kelly bankrolls regularly swing 50%+. Most pros take a quarter of the recommended stake — way less volatility, only modest growth penalty.
Our /tools/bankroll calculator caps suggestions at quarter-Kelly so the recommended stake actually survives the variance on small bankrolls. If you're playing a positive-EV bet, that's the stake. If Kelly returns zero or negative, the calculator surfaces that honestly.
Frequently asked questions
- Should I use Kelly on every bet?
- Only positive-EV ones. For every casino game without bonus stacking, Kelly returns zero. That's the correct answer.
- Why does Kelly recommend zero?
- Because the game has negative EV. The formula is honest about it. Anything you bet loses money long-run.
- What's quarter-Kelly?
- A quarter of the full Kelly stake. Reduces variance dramatically. Standard pro practice.
- How do I find positive-EV opportunities?
- Stack rakeback on low-edge games like Mines or Blackjack. At Yeti rakeback on Mines, the effective edge can tip positive. /tools/bankroll handles the math.