Poker Bankroll Management: buy‑ins, Risk of Ruin and Simple Rules
Poker bankroll management means keeping a separate sum of money for poker and playing stakes small enough that a normal losing streak cannot wipe it out. A common guideline is 20 to 30 buy‑ins for cash games and 100 or more for tournaments, but the right number depends on your win rate: the smaller your edge, the bigger the bankroll you need. It protects a winning player from variance; it cannot turn a losing player into a winner.
What a bankroll is, and what it is not
- Separate money: only money you can afford to lose, kept apart from rent, savings and everyday spending. Never borrowed.
- A buy‑in is the unit: in no-limit cash games, one buy‑in is usually 100 big blinds; in tournaments, it is the entry fee.
- Not a strategy: a bankroll does not win pots. Your decisions do; the bankroll only keeps you in the game long enough for them to count.
How many buy‑ins: the usual guidelines
| Format | Common guideline |
|---|---|
| Cash game, no-limit | 20 to 30 buy‑ins |
| Tournaments | 100 buy‑ins or more |
Tournaments need far more buy‑ins because most entries finish without a prize, so the swings are much larger.
Risk of ruin: the numbers behind the rule
The risk of ruin is the probability of eventually losing the whole bankroll if you keep playing the same stake forever, without topping up or moving down. A classic approximation gives it as exp(−2·w·B/σ²), where w is your win rate, B your bankroll and σ the standard deviation of your results. The table below uses two assumed win rates, 5 and 2.5 big blinds per 100 hands, with a standard deviation of 100 big blinds per 100 hands (an assumption, not a measurement) and 100 big blinds per buy‑in.
| Bankroll | Win rate 5 bb/100 | Win rate 2.5 bb/100 |
|---|---|---|
| 20 buy‑ins | 13.5% | 36.8% |
| 30 buy‑ins | 5.0% | 22.3% |
| 50 buy‑ins | 0.7% | 8.2% |
| 100 buy‑ins | under 0.1% | 0.7% |
Halving your win rate gives the same risk only with twice the bankroll. And the formula assumes you really are a winning player at that rate: if you are not a winning player at all, the risk of ruin is 100%, whatever the bankroll.
Moving up and moving down
- Set the rule before you sit down: for example, move down one level if you fall from 30 to 20 buy‑ins.
- Move up with a cushion: only once you have the full guideline for the next stake, not after a single good session.
- Cap any try at a higher stake: if you try a higher stake, set aside a fixed number of buy‑ins for it and go back down when they are gone.
Three common mistakes
- Chasing losses: raising the stakes to win it back, often while tilted.
- Mixing poker money with living money: the bankroll stops being a limit.
- Ignoring variance: a losing week is normal even for a winning player; it says little about your level.
Play responsibly
Poker with money is for adults (18+). Only play what you can afford to lose. If it stops being fun, contact a gambling support service in your country. To improve without risking anything, practice poker without money.
Keep going
- Why results swing so much: poker variance.
- Stay in control after a bad beat: poker tilt.
- The math of every call: pot odds.
- A plan to improve: get better at poker in 30 days.
- Train your decisions for free: our free poker trainer.
- What a decision is worth on average: expected value in poker.
- What tournament chips are really worth: ICM poker.
Sources
- buy‑in guidelines as commonly given by poker strategy guides (e.g. thepokerbank.com, "Bankroll Management").
- Risk-of-ruin approximation as presented in Chen and Ankenman, The Mathematics of Poker (2006); table computed by the author (October 10, 2026) with the stated assumptions.