How much bankroll do I need to play a given stake?

It depends on your win rate and your game's variance (standard deviation), plus how much risk of going broke you're willing to accept. This calculator uses the standard risk-of-ruin formula — the poker-specific application of the Kelly criterion — to turn those three inputs into a buy-in count.

What is risk of ruin?

The probability that, over a long enough run of variance, you go broke before your win rate pulls you ahead — even though you have a genuine edge. A smaller bankroll relative to your edge and variance means a higher risk of ruin.

What's a typical standard deviation for cash games?

Full-ring No-Limit Hold'em cash games are commonly cited around 80-100bb/100 hands; 6-max and looser games run higher. Tournament variance is much larger and this bb/100-based formula isn't the right tool for tournament bankroll sizing.

Why does a losing win rate return 'no answer'?

The risk-of-ruin math only works for a player with a genuine positive edge. If your win rate is zero or negative, no bankroll size mathematically guarantees you avoid eventual ruin at that stake — the fix is to move down in stakes or work on your win rate, not to add more buy-ins.

Does this calculator know my actual win rate?

No — it's a standalone arithmetic tool. You supply your own tracked win rate and standard deviation (from your own hand-history tracking software or a rough estimate), and it converts that into a buy-in recommendation.

Poker Bankroll Calculator

Figure out how many buy-ins you need at a given stake, based on your win rate, variance, and how much risk of going broke you can tolerate.

Win rate (bb/100)Std dev (bb/100)Desired risk of ruin (%)Buy-in size (bb)

Recommended bankroll30.3 buy-ins

In big blinds3,033bb

At a 5bb/100 win rate with 90bb/100 std dev, you need roughly 30.3 buy-ins (3033bb) to keep risk of ruin under 5%, including a 25% safety cushion.

Why this matters more than a fixed buy-in rule

Generic advice like "20 buy-ins for cash games" ignores that a strong winning player and a marginal winning player need very different bankrolls at the same stake. This calculator ties the number directly to your actual edge and variance instead of a one-size-fits-all rule of thumb.

How this calculator works — formulas & method

Method: Kelly-criterion risk-of-ruin formula (standard poker derivation) · deterministic arithmetic — no AI

Constant	Value	Source
winRate	your bb/100 win rate	user input
stdDev	your game's bb/100 standard deviation	user input, typically 80-100 for full-ring cash
desiredRoR	acceptable probability of going broke	user input, e.g. 0.05

— Risk-of-ruin bankroll size —bankrollBb = (stdDev² / (2 × winRate)) × ln(1 / desiredRoR)bankrollBb *= safetyMarginbuyIns = bankrollBb / 100 // undefined when winRate <= 0 — no bankroll makes a losing// or break-even player immune to eventual ruin

Deterministic arithmetic, standard Kelly-criterion derivation for poker bankroll sizing. Not investment or financial advice — a mathematical model of variance, not a guarantee.

FAQ

How much bankroll do I need to play a given stake?: It depends on your win rate and your game's variance (standard deviation), plus how much risk of going broke you're willing to accept. This calculator uses the standard risk-of-ruin formula — the poker-specific application of the Kelly criterion — to turn those three inputs into a buy-in count.
What is risk of ruin?: The probability that, over a long enough run of variance, you go broke before your win rate pulls you ahead — even though you have a genuine edge. A smaller bankroll relative to your edge and variance means a higher risk of ruin.
What's a typical standard deviation for cash games?: Full-ring No-Limit Hold'em cash games are commonly cited around 80-100bb/100 hands; 6-max and looser games run higher. Tournament variance is much larger and this bb/100-based formula isn't the right tool for tournament bankroll sizing.
Why does a losing win rate return 'no answer'?: The risk-of-ruin math only works for a player with a genuine positive edge. If your win rate is zero or negative, no bankroll size mathematically guarantees you avoid eventual ruin at that stake — the fix is to move down in stakes or work on your win rate, not to add more buy-ins.
Does this calculator know my actual win rate?: No — it's a standalone arithmetic tool. You supply your own tracked win rate and standard deviation (from your own hand-history tracking software or a rough estimate), and it converts that into a buy-in recommendation.