How to use the risk of ruin calculator
- Enter your win rate in big blinds per 100 hands.
- Enter your standard deviation in bb/100 (around 80 for 6-max no-limit hold'em).
- Enter your bankroll in buy-ins (100 big blinds each) or in dollars with your big blind size.
- Choose a target risk to see the bankroll you'd need to reach it.
What is risk of ruin?
Risk of ruin (RoR) is the probability that you lose your entire bankroll at some point, assuming you keep playing the same game at the same stakes forever. It depends on three things: how much you win, how much your results swing, and how big your bankroll is.
Risk of ruin = e−2 × win rate × bankroll ÷ SD²
(win rate and SD in bb/100, bankroll in big blinds)
The formula shows two important things: doubling your bankroll squares your risk (5% becomes 0.25%), and a small improvement in win rate reduces risk dramatically.
Risk of ruin examples
| Win rate | SD | Bankroll | Risk of ruin |
|---|---|---|---|
| 5 bb/100 | 80 | 20 buy-ins | 4.4% |
| 5 bb/100 | 80 | 30 buy-ins | 0.9% |
| 2 bb/100 | 80 | 30 buy-ins | 15.3% |
| 10 bb/100 | 80 | 20 buy-ins | 0.2% |
A 5 bb/100 player needs about 29.5 buy-ins for 1% risk of ruin and about 19 buy-ins for 5%. A 2 bb/100 player needs 2.5× as much for the same risk.
Limitations
- Your true win rate is uncertain. If you overestimate it, your real risk is higher. Use a conservative number.
- The model assumes you never move down. Good bankroll management with move-down rules lowers your real risk a lot.
- It's designed for cash games. For tournaments, use buy-in guidelines from the bankroll calculator.
Risk of ruin FAQ
What is an acceptable risk of ruin?
Professionals usually aim for 1% or less. Recreational players who can reload from income can accept 5–10%.
What if my win rate is zero or negative?
Your risk of ruin is 100% — eventually you will lose any bankroll. Focus on improving your game and playing lower stakes.
Where do I find my standard deviation?
Online tracking software reports it. Otherwise use 75–85 for 6-max NLHE. See how SD affects swings with the variance calculator.