Risk of ruin calculator
Risk of ruin is your chance of losing your whole bankroll if you keep playing the same stakes for good. Put in your win rate, your swing and your bankroll to see yours, and what it takes to bring it down.
The formula trusts your win rate completely. Measured over a few hundred hours, it could easily be half what you think — and at half the win rate you need twice the bankroll for the same risk.
Your win rate pulls your bankroll up; your swings push it around. The bigger your bankroll is next to your swings, the less chance one long downswing takes all of it. The standard result for that kind of random walk is:
Win rate and swing just have to be counted the same way — both per hour, or both per 100 hands — and the bankroll in big blinds.
Solve it for the bankroll to get the size for any risk you're willing to take:
At 5 bb an hour with a 70 bb swing, a 5% risk takes about 1,500 big blinds — 15 buy-ins — and a 1% risk about 2,300. Online, at 4 bb/100 with a swing of 90, it's about 3,000 and 4,700.
The formula treats your win rate as known. It isn't: after a few hundred hours, the true figure could easily be half what you've measured, and half the win rate needs twice the bankroll for the same risk. That's why the answer above shows your risk at half your win rate too. The win rate calculator shows how wide that uncertainty is.
It also assumes you never move down. Dropping a level after a big downswing — which is what most bankroll rules amount to — cuts the real risk a lot. Treat the number as the risk of stubbornly staying put.
Session tracker
Log your sessions — balance before and after, when you sat down and stood up — and PotCheck works out your real hourly, your swing, the range your win rate is really in, and your risk of ruin. Free, no ads.
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