Risk of Ruin Calculator
The exact odds your bankroll busts before you walk away.
| Bankroll (units) | Risk of ruin |
|---|---|
| 10 | 44.91 % |
| 25 | 13.52 % |
| 50 | 1.83 % |
| 100 | 0.03 % |
| 200 | 0.00 % |
How it works
Risk of ruin is the probability your bankroll hits zero before you stop, assuming flat even-money bets. With a positive edge it is (q ÷ p) raised to the number of units in your bankroll, where p is your win probability and q = 1 − p.
Two levers cut the risk: a bigger edge and more betting units (a smaller bet relative to the bankroll). Without an edge — win probability 50% or below — ruin is certain over enough bets, no matter how large the bankroll. This is the analytic complement to the Monte-Carlo simulator.
Risk of Ruin Calculator
Risk of ruin is the probability that your bankroll hits zero before you stop playing. This free calculator gives the exact figure for flat, even-money bets straight from the gambler's ruin formula — the analytic complement to the Monte-Carlo simulator, with no simulation needed.
The gambler's ruin formula
For flat even-money bets, risk of ruin depends on just two things: your edge and how many bet-sized units your bankroll holds. With win probability p and loss probability q = 1 − p, and a bankroll of N units, the risk of ever going broke is (q ÷ p) raised to the power N — provided you have an edge (p > 0.5).
Without an edge the answer is stark: if p is 50% or less, ruin is certain over a long enough run, regardless of how big the bankroll is. A fair game with no edge always busts eventually.
How to shrink the risk
Two levers reduce risk of ruin. The first is a bigger edge — even a small one drops the risk sharply because it is raised to the power of the unit count. The second is more units: betting a smaller fraction of your bankroll multiplies the exponent, so the same edge protects you far better with 100 units than with 10.
This is the mathematical backbone of bankroll management and the Kelly criterion. The model assumes even-money payouts and a fixed flat stake; uneven payouts or progression staking change the curve, which is where the Monte-Carlo simulator takes over.
What is risk of ruin?expand_more
The probability that a bettor or gambler loses their entire bankroll before stopping. It depends on the edge, the bet size relative to the bankroll, and the payout structure.
How do you calculate risk of ruin?expand_more
For flat even-money bets it is (q ÷ p) raised to the number of bankroll units, where p is your win probability and q = 1 − p. With no edge (p ≤ 0.5) ruin is certain.
How can I reduce my risk of ruin?expand_more
Increase your edge and bet a smaller fraction of your bankroll. More betting units and a positive edge both push the probability of going broke down quickly.
Is risk of ruin ever zero?expand_more
Not with real bets — a long enough losing streak is always possible. A genuine edge and a large unit count can make it negligibly small, but never exactly zero.