Poker Bankroll Calculator
Enter your win rate and standard deviation. The calculator estimates the risk of ruin for the bankroll you hold, the buy-ins needed for a target risk, and how results spread over a number of hands.
Average profit per 100 hands. Take it from your tracker; 5 is a strong result.
How widely results swing. No-limit hold'em is often 80 to 100.
A cash-game buy-in is usually 100 big blinds.
How many buy-ins of this size you hold.
Risk of ruin
- Risk of ruin
- 0.92%
- Bankroll in big blinds
- 3,000
Buy-ins for a target risk
- 5% risk: 19.2 buy-ins
- 1% risk: 29.5 buy-ins
- 0.5% risk: 33.9 buy-ins
Results over a sample of hands
For example 10,000.
- Expected profit
- +500 bb
- Typical spread (±1 standard deviation)
- ±800 bb
- Chance of being behind
- 27%
Model: constant stakes, normally distributed results, you never move down. Tournaments are more volatile than this, so the figures are optimistic for them.
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How the numbers are calculated
Two numbers describe a cash-game player: the win rate, your average profit per 100 hands, and the standard deviation, how widely results spread around it. With a win rate of 5 bb/100 and a standard deviation of 80 bb/100, the expected profit over n hundred hands is 5 × n big blinds, but the typical spread is 80 × √n. Profit grows faster than spread, so the edge shows only over a large sample.
The risk of ruin is the chance of ever losing the whole bankroll. For constant stakes it is approximately exp(−2 × win rate × bankroll ÷ standard deviation²), with the bankroll in big blinds. The more buy-ins you hold, the faster the risk falls; a lower win rate or a higher standard deviation pushes it up.
The calculator also turns the formula around: it shows how many buy-ins keep the risk at 5%, 1% or 0.5%. With the example numbers that is about 19 buy-ins for 5% and about 29 for 1%, which fits the common guideline of 20 to 40 buy-ins for cash games.
Worked example
A player with 5 bb/100 and 80 bb/100 holds 30 buy-ins of 100 big blinds, which is 3,000 big blinds. The risk of ruin is exp(−2 × 5 × 3,000 ÷ 6,400) ≈ 0.9%. With 20 buy-ins it rises to about 4.4%.
The same player over 10,000 hands expects +500 big blinds with a typical spread of ±800, and is still behind in about 27% of such samples. A clear winner can lose for a long time, which is exactly what the bankroll is for.
Questions and answers
What is risk of ruin in poker?
The probability that you eventually lose your whole bankroll while playing the same stakes. It depends on your win rate, your standard deviation and the number of buy-ins you hold.
Which win rate and standard deviation should I use?
Take both from your own tracking software over a large sample, ideally tens of thousands of hands. For no-limit hold'em a standard deviation of 80 to 100 bb/100 is typical. A win rate you are unsure of should be entered conservatively.
Why is the risk 100% when my win rate is zero?
Without a positive edge the random walk eventually hits any lower barrier, so a bankroll only delays ruin. The model needs a win rate above zero to return a lower number.
Does this work for tournaments?
Only roughly. Tournament results are far more volatile and the prize pool is concentrated at the top, so the real risk is higher than the model shows and 50 to 100 or more buy-ins are common.
Related guides
The calculator is an educational tool, it does not predict results and is not financial advice. Play only with money you can afford to lose: responsible gambling.