Poker Downswing Probability Calculator
Calculate the likelihood of experiencing a specific downswing size based on your win rate, variance, and sample size to prepare for inevitable variance.
Formula:P(Result ≤ -X) using normal distribution
Your expected win rate in big blinds per 100 hands
Typical: 70-90 for cash, 100-150 for tournaments
Sample size to analyze
Downswing amount in big blinds (e.g., 1000 = 10 BI)
For converting to currency values
Try These Examples
Quick-start with common scenarios
Bankroll Simulator
Monte Carlo simulation with 1,000 iterations
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Your initial capital
%
Your expected advantage
%
Percentage of bankroll per bet
Total bets to simulate
Understanding Poker Downswings
A downswing is a period where your results are significantly below expectation. They're mathematically inevitable in poker and happen to every player.
The Math: We use the normal distribution to calculate probability. Your results follow a bell curve centered on your expected value, with spread determined by standard deviation.
Sample Size Matters: In small samples (under 30,000 hands), even large downswings are normal. A 3 BB/100 winner has about a 30% chance of being down after 20,000 hands.
Mental Game: Understanding that downswings are expected helps maintain emotional stability. When you know a 10-buyin downswing has a 15% chance of occurring, it's easier to stay focused on making good decisions rather than results.
Practical Advice: Always have a bankroll that can withstand a 20-30 buyin downswing. If you can't handle the swings at your stakes, move down.
Frequently Asked Questions
How likely is a 10 buyin downswing?
For a typical 5 BB/100 winner with 80 BB/100 SD, a 10 buyin downswing will happen roughly once every 50,000-100,000 hands. Even excellent players averaging $25/hour experience 1000 BB ($5,000 at $2/$5) downswings.
Why do I keep having downswings?
Downswings are a mathematical certainty in poker, not a sign of bad play. A 3 BB/100 winner has about a 40% chance of being down after 10,000 hands. Only after 100,000+ hands do results become statistically meaningful.
How long do downswings last?
Downswing duration varies wildly. A 20 buyin downswing for a 5 BB/100 winner might last 30,000-50,000 hands (300-500 hours of play). Tournament players can have year-long downswings due to extreme variance.
Should I move down during a downswing?
If your bankroll drops below 20 buyins for your current stake, yes. This protects your bankroll and reduces stress. Many pros use a 'stop-loss' rule - move down after losing 3-5 buyins in a session.
How do I mentally handle downswings?
Focus on making good decisions, not results. Track your decisions separately from outcomes. Take breaks when frustrated. Remember that downswings are part of the game and mathematically expected.
How this works
Calculations follow the published mathematics of the game — combinatorics for cards, probability theory for dice, and expected-value accounting for wagers. Results are verified against independent references (primarily Wizard of Odds). No calculation here is an opinion or recommendation; it is arithmetic applied to the rules of the game.
What this tool can’t do
When to consult a professional
This tool computes probability and expected value. It is not a betting system and cannot predict the outcome of any individual wager. If gambling is causing problems for you or someone you know, call the National Problem Gambling Helpline at 1-800-GAMBLER.
Sources
- [1]Wizard of Odds — Michael Shackleford, ASAIndustrywizardofodds.comAccessed Apr 21, 2026
Actuary; widely cited casino-game probability reference. Used for house-edge and EV verification.
- [2]National Council on Problem GamblingOfficial sourcencpgambling.orgAccessed Apr 21, 2026
Responsible-gambling guidance and 1-800-GAMBLER helpline.
Joseph OrdunaFounder & Software Engineer
Full-stack software engineer specializing in embedded systems, web architecture, and AI/ML. Founder of Practical Web Tools. Built the gesture-controlled drone IP acquired by KD Interactive (Aura Drone, sold on Amazon).