Poker Bankroll Calculator: Risk of Ruin & Buy-ins (2026)
Most bankroll advice stops at a flat rule like 20 or 30 buy-ins. This calculator goes further: it plugs your actual win rate and standard deviation into the risk-of-ruin formula, then tells you both your current risk and the bankroll you need for the safety level you pick.
Your edge
Your money
Risk profile
The chance of losing the whole bankroll you are willing to accept. Lower means safer, but you need more buy-ins.
Well bankrolled
Bankroll you need
To keep your risk of ruin at or below 2.5% with these inputs, this is the bankroll and buy-in count you should hold.
Moving stakes
You would drop to 25 buy-ins there, above your risk target. Build more first or take a short shot with a stop-loss.
Risk of ruin vs bankroll
How your ruin risk drops as you add buy-ins, at your current win rate and standard deviation.
Risk of ruin by stake
| Stake | Buy-ins | Risk of ruin |
|---|---|---|
| NL2$0.01/$0.02 | 2,500 | <0.1% |
| NL5$0.02/$0.05 | 1,000 | <0.1% |
| NL10$0.05/$0.10 | 500 | <0.1% |
| NL25$0.10/$0.25 | 200 | <0.1% |
| NL50$0.25/$0.50 | 100 | <0.1% |
| NL100$0.50/$1 | 50 | 0.2% |
| NL200$1/$2 | 25 | 4.6% |
| NL500$2.50/$5 | 10 | 29.1% |
| NL1000$5/$10 | 5 | 53.9% |
| NL2000$10/$20 | 3 | 73.4% |
Same bankroll, same skill. Only the stake changes, so the buy-in count and risk of ruin change with it. Green means within your risk target.
Poker bankroll management: the math behind the rules
Ask ten winning players how big a poker bankroll should be and you get ten numbers. As of 2026 the honest answer is that there is no single figure, because the right size depends on three things only: how much you win, how wildly your results swing, and how much risk you can stomach. This calculator turns those three inputs into one number you can act on.
What a bankroll actually protects against
Your bankroll is not your spending money. It is the buffer that keeps a normal downswing from ending your poker. Even a strong winner loses for weeks at a time. The bankroll exists so those stretches stay survivable instead of busting you back to zero.
The thing it protects against has a name: risk of ruin. That is the probability that variance drags you to zero before your edge can pull you back up. A bigger edge lowers it, more variance raises it, and a bigger bankroll lowers it. The whole job of bankroll management is keeping that number small enough to sleep at night.
Flat rules like 20 or 30 buy-ins are shortcuts for this math. They are fine starting points, but they assume an average win rate and average variance. If you win less than average or play a high-variance game like PLO, the same 20 buy-ins carry far more risk than the rule implies.
I have run the same bankroll through this formula and through a Monte Carlo simulator side by side for years. The analytic number and the simulated one land within a hair of each other for cash games, which is why I trust the formula for quick sizing and save the simulator for downswing depth.
The risk-of-ruin formula, in plain English
For a cash game, risk of ruin has a clean closed form. With your win rate and standard deviation both measured per 100 hands, and your bankroll measured in big blinds, the chance of going broke is:
Read it like this: the bigger your win rate or your bankroll, the more negative the exponent, so the risk shrinks fast. The bigger your standard deviation, the smaller the exponent, so the risk grows. Squaring the standard deviation is why variance matters so much: doubling your swings quadruples their pull on the exponent.
Turn the formula around and you get the reverse question this tool answers by default. Pick the risk you accept, say 5%, and it solves for the bankroll that hits exactly that number. For a 5 bb/100 winner with a 90 bb/100 standard deviation, that comes out to about 24 buy-ins for 5%, 30 for 2.5%, and 37 for 1%.
How to use the bankroll calculator on toolsgambling.com
On toolsgambling.com you can use this poker bankroll calculator for free, just like all our other tools. Here is the fastest way to a number you trust.
- 1Load a preset, then tune it.Pick the preset closest to your game to fill in a realistic win rate and standard deviation, then overwrite both with your own tracker numbers if you have them.
- 2Set your real bankroll and buy-in.Enter the money you actually keep for poker and the buy-in you play, so the tool counts buy-ins correctly.
- 3Choose the risk you accept.One percent is cautious, five percent is aggressive. The required bankroll moves with this choice.
- 4Check the stake ladder.The table shows your risk of ruin at every stake for the same bankroll, so you can see exactly where you are safe.
- 5Act on the move up or move down call.If a higher stake stays inside your target, a shot is reasonable. If your current stake is over target, drop down and rebuild.
Why the formula beats a flat buy-in rule
A fixed rule is one number for every player. The formula adapts to who you actually are. Four cases show why that matters.
Smaller edge, bigger roll
A 1 bb/100 grinder needs roughly 121 buy-ins for the same 5% risk a 5 bb/100 winner clears with 24. A flat rule hides that gap completely.
Game changes everything
At 40 buy-ins and the same 5 bb/100 win rate, NLHE sits near 0.7% risk while PLO with its bigger swings jumps to about 9.4%. Variance, not skill, drives the difference.
20 buy-ins is often not enough
A 3 bb/100 winner with 90 standard deviation still carries about 23% risk of ruin at 20 buy-ins. That is a one-in-four chance of busting, which most players would never accept if they saw the number.
Your risk tolerance is personal
A recreational player and a pro paying rent should not use the same number. The formula lets you set the risk you accept instead of inheriting someone else's.
Buy-ins needed by risk profile
These figures use a solid 6-max example: a 5 bb/100 win rate and a 90 bb/100 standard deviation. Your own numbers will shift them, which is exactly why the calculator exists.
| Profile | Target risk | Buy-ins |
|---|---|---|
| Conservative | 1% | 37 |
| Standard | 2.5% | 30 |
| Aggressive | 5% | 24 |
Example only, for a 5 bb/100 winner at 90 bb/100 standard deviation. Lower your win rate or raise your variance and every number climbs.
Bankroll mistakes that quietly bust players
Treating winnings as bankroll too early.
A good month is not a new edge. Move up on buy-in count and a stable win rate over a real sample, not on a hot streak.
Ignoring standard deviation.
Two players with the same win rate can need wildly different bankrolls. The one playing loose, high-variance pots needs far more cushion.
Using cash rules for tournaments.
Top-heavy payouts make tournament variance brutal. Even strong MTT players run 100 buy-ins deep or more for a reason.
Never moving down.
Dropping a level is not failure, it is the single fastest way to cut variance and protect the roll during a downswing.
Tournament bankroll: why MTT and Spin & Go need more
Tournaments break the cash formula. Top-heavy payouts mean you lose your buy-in most of the time and bank the bulk of your profit from rare deep runs and final tables. That makes results lumpy instead of the smooth per-100-hand swings a cash model assumes, so the clean risk-of-ruin equation simply does not fit. A winning MTT regular can fire a hundred buy-ins without a single cash and still be a long-term winner. The bankroll has to absorb that.
Because of this, the field runs on buy-in counts, not a formula. A common floor is around 100 buy-ins for multi-table tournaments, dropping to roughly 50 for single-table Sit and Gos, and climbing to 150 or more for Spin and Go, where the random multiplier piles extra variance on top of the usual tournament swings. Cautious pros hold 200 or more for big-field MTTs. Switch the tool to your format, enter your average buy-in, and pick a profile to see the floor in dollars.
Treat that number as a floor, not a finish line. Tournament downswings run longer than cash ones, so move down sooner and without ego when your roll dips. Pull your real ITM and ROI from your tracker instead of guessing, and remember that one big score can hide a leaky game. On toolsgambling.com the same page handles cash and all three tournament formats, so you can size every part of your schedule in one place.
Bankroll terms, defined
- Risk of ruin
- The probability that variance takes your bankroll to zero before your edge recovers it. The core number this tool computes.
- Win rate (bb/100)
- Big blinds won per 100 hands. The standard cash-game measure of your edge. Five bb/100 is a solid winner online.
- Standard deviation
- How much your results swing around your average, also in bb/100. Typical NLHE sits near 75 to 100, PLO higher. Pull yours from PokerTracker or Hold'em Manager.
- Buy-in
- One full stake. In cash that is 100 big blinds; in tournaments it is the entry fee. Bankrolls are measured in buy-ins so they compare across stakes.
- Downswing
- A sustained stretch of losing or break-even results inside a winning career. Normal, expected, and the whole reason a bankroll exists.
- Shot taking
- Playing a higher stake than your bankroll fully supports, usually with a strict stop-loss, to test the level without committing your whole roll.
Free poker tools on toolsgambling.com
Bankroll sizing is one piece. Pair it with these free tools to see the variance behind the number and to grow the roll once it is the right size.
Play within your means
A bankroll is also a discipline tool. If poker stops being fun or the money stops being money you can lose, take a break and get support at BeGambleAware.org.
Evgeniy Volkov
Fullstack developer with a background in mathematics. I build the calculators and game-style tools on ToolsGambling with Pixi.js and modern web tech, and every result uses transparent probability formulas you can verify yourself.
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