Bust Probability Calculator
Calculate your probability of going bust (ruin) based on bankroll, bet size, and game odds. Understand the math behind gambling risk before you play.
Parameters
Results
How Bust Probability Works
The Gambler's Ruin Problem
The Gambler's Ruin is a classic problem in probability theory. It models a gambler who starts with a finite bankroll and repeatedly makes fixed-size bets on a game with known odds. The central question: what is the probability that the gambler eventually loses everything?
When the game has a negative expected value (as most casino games do), the probability of eventual ruin approaches 100% given enough bets. Even with a slight house edge, the longer you play, the more certain it becomes that you will go bust.
Risk of Ruin Formula
For a simple win/loss game with fixed bet size, the classic Risk of Ruin (RoR) formula is derived from the Gambler's Ruin theorem:
If p != q:
RoR = (q / p) ^ B
If p == q (fair game):
RoR = 1 (certain ruin)
Where:
p = win probability
q = 1 - p
B = bankroll / bet_size The Kelly Criterion
The Kelly Criterion is a formula for determining the optimal bet size to maximize the long-term growth rate of your bankroll:
Kelly % = edge / (multiplier - 1)
Where:
edge = p * (multiplier - 1) - (1 - p)
p = win probability
multiplier = payout multiplier Why Bankroll Management Matters
Even with a positive expected value, poor bankroll management can still lead to ruin. Overbetting relative to your bankroll dramatically increases the chance of hitting a losing streak that wipes you out before the edge has time to materialize.
Discipline in bet sizing is the single most important factor in long-term survival. A player risking 1% per bet with a 2% edge has near-zero probability of ruin. The same player risking 20% per bet has significant bust risk.
Want More Tools Like This?
GAMB·8 gives you automated betting strategies, real-time analytics, and professional-grade bankroll management tools. Sign up for free and take your game to the next level.