Variance & downswings
Variance is the swing around your true win rate. A solid winner will still endure brutal losing stretches, which is why you judge your game over tens of thousands of hands, not a single session — watch it play out in the downswing simulator.
Variance is the gap between skill and results
Your true win rate is how much you'd win per 100 hands if you played forever. Variance is the noise layered on top of it: the reason a great player can lose for weeks and a bad player can win for a weekend. Over a single session, luck dominates. Over a huge sample, skill does. The whole game of studying results is separating the two.
Even a strong favorite loses often
Get it in with aces against a single opponent's random hand and you win about 85% of the time. Great odds. But run that spot seven times and, on average, one of them cracks. String a few of those beats together in one night and it feels like the deck is out to get you. It isn't. You're just watching the 15% show up in a small sample.
Standard deviation: measuring the swings
Poker software reports a standard deviation in bb/100, typically around 80–100 for full-ring and 90–120+ for aggressive short-handed play. It quantifies how spread out your results are. A higher standard deviation means bigger swings in both directions — which is why a 5 bb/100 winner with 100 bb/100 standard deviation can easily be buried for tens of thousands of hands before the edge surfaces.
Variance simulator
A winning player still has losing months. Set your win rate and how swingy your game is, and watch the range of results luck can hand you.
- Expected result
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- 95% of results land in
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- Chance you're in profit
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- Risk of ruin
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Assumes results are normally distributed with a fixed win rate — a good model over tens of thousands of hands. Real edges drift, and short samples swing far more, so treat the bands as a guide, not a guarantee.
Why sessions lie and samples tell the truth
A session is a few hundred hands — pure noise. Even a month can be a downswing for a winning player. Serious evaluation happens over tens of thousands of hands, where the standard deviation of your average win rate shrinks and your true skill emerges. Judge your game by decisions and long-run numbers, not by whether tonight's graph went up.
- Your true win rate is a long-run number; variance is the noise around it that dominates any short session.
- Standard deviation in bb/100 (roughly 80–120) measures how big your swings are — higher means longer stretches away from your true rate.
- Even an 85% favorite loses about 1 in 7 times, so downswings for winning players are guaranteed, not a sign of a broken game.
- Evaluate your play over tens of thousands of hands and keep a bankroll of many buy-ins to survive the inevitable swings.
Test yourself
Answer them all — 16/20 to pass. Every answer gets an explanation.
What does 'variance' describe in poker?
Variance is the spread of short-term results around your true win rate, caused by luck.
In what units is win rate typically measured in tracking software?
Win rate is standardized as big blinds per 100 hands so it's comparable across stakes.
Roughly how often do pocket aces lose all-in preflop against a single random hand?
Aces are roughly an 85% favorite heads-up, so they lose about 15% of the time.
What does standard deviation in bb/100 tell you?
Standard deviation measures the dispersion of results; higher means bigger swings.
Why is a single session a poor way to judge your skill?
Over a small sample, variance overwhelms skill, so one session is mostly noise.
A winning player with a positive win rate can still:
Downswings can last many thousands of hands even for genuine long-term winners.
Which of these tends to have a HIGHER standard deviation?
Aggressive short-handed games create bigger pots and wider ranges, raising variance.
AK suited all-in preflop against a small pair like 22 is closest to:
Two overcards versus a pair is famously close to a 50/50 flip.
What is the main purpose of a large bankroll?
A bankroll cushions the normal, mathematically inevitable losing stretches.
As your sample of hands grows very large, what happens?
Over huge samples, luck averages out and true skill dominates the results.
Even 72 offsuit, the worst starting hand, all-in preflop against pocket aces wins about:
Nothing is ever a lock; even the worst hand wins roughly one time in eight against aces.
A downswing for a winning player is best described as:
Variance guarantees losing stretches even when your underlying edge is real.
Which statement about win rate is correct?
Win rate is a long-term expectation; individual sessions scatter around it.
Two players have the same 5 bb/100 win rate but different standard deviations. The higher-SD player will:
Same edge but more dispersion means larger upswings and downswings alike.
Roughly how many hands is a reasonable sample to start judging a cash-game win rate?
You need tens of thousands of hands before results reflect your true rate.
If a favorite is 85% to win, over many trials it will lose:
An 85% favorite by definition loses the remaining 15% of the time.
Which factor does NOT directly reduce the impact of variance on your assessment?
One big session is itself a tiny, noisy sample and tells you little about skill.
A player claims the site is rigged after losing with aces three times in one night. A better explanation is:
Losing with aces multiple times in a small sample is ordinary variance.
Higher variance in your results means you should generally keep:
Bigger swings require more buy-ins in reserve to avoid going broke.
The right mindset toward a downswing while your play is sound is to:
If decisions are sound, variance is the cause and results will recover over volume.
Review — all 20 questions & answers tap to expand
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What does 'variance' describe in poker?
Answer The swing of results around your true long-term win rate
Variance is the spread of short-term results around your true win rate, caused by luck.
-
In what units is win rate typically measured in tracking software?
Answer Big blinds per 100 hands (bb/100)
Win rate is standardized as big blinds per 100 hands so it's comparable across stakes.
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Roughly how often do pocket aces lose all-in preflop against a single random hand?
Answer About 1 time in 7 (around 15%)
Aces are roughly an 85% favorite heads-up, so they lose about 15% of the time.
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What does standard deviation in bb/100 tell you?
Answer How spread out your results are — the size of your swings
Standard deviation measures the dispersion of results; higher means bigger swings.
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Why is a single session a poor way to judge your skill?
Answer A few hundred hands is too small a sample; luck dominates
Over a small sample, variance overwhelms skill, so one session is mostly noise.
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A winning player with a positive win rate can still:
Answer Be down money over tens of thousands of hands
Downswings can last many thousands of hands even for genuine long-term winners.
-
Which of these tends to have a HIGHER standard deviation?
Answer Aggressive short-handed play
Aggressive short-handed games create bigger pots and wider ranges, raising variance.
-
AK suited all-in preflop against a small pair like 22 is closest to:
Answer A coin flip, about 50/50
Two overcards versus a pair is famously close to a 50/50 flip.
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What is the main purpose of a large bankroll?
Answer To survive inevitable downswings without going broke
A bankroll cushions the normal, mathematically inevitable losing stretches.
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As your sample of hands grows very large, what happens?
Answer Your observed results converge toward your true win rate
Over huge samples, luck averages out and true skill dominates the results.
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Even 72 offsuit, the worst starting hand, all-in preflop against pocket aces wins about:
Answer 12% of the time
Nothing is ever a lock; even the worst hand wins roughly one time in eight against aces.
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A downswing for a winning player is best described as:
Answer A normal, expected outcome of variance
Variance guarantees losing stretches even when your underlying edge is real.
-
Which statement about win rate is correct?
Answer It's a long-run average, not a result you hit every session
Win rate is a long-term expectation; individual sessions scatter around it.
-
Two players have the same 5 bb/100 win rate but different standard deviations. The higher-SD player will:
Answer Experience bigger swings in both directions
Same edge but more dispersion means larger upswings and downswings alike.
-
Roughly how many hands is a reasonable sample to start judging a cash-game win rate?
Answer Tens of thousands of hands
You need tens of thousands of hands before results reflect your true rate.
-
If a favorite is 85% to win, over many trials it will lose:
Answer About 15% of the time
An 85% favorite by definition loses the remaining 15% of the time.
-
Which factor does NOT directly reduce the impact of variance on your assessment?
Answer Winning a single big session
One big session is itself a tiny, noisy sample and tells you little about skill.
-
A player claims the site is rigged after losing with aces three times in one night. A better explanation is:
Answer Aces lose 15% of the time, so short-run clusters are normal
Losing with aces multiple times in a small sample is ordinary variance.
-
Higher variance in your results means you should generally keep:
Answer A larger bankroll to absorb the swings
Bigger swings require more buy-ins in reserve to avoid going broke.
-
The right mindset toward a downswing while your play is sound is to:
Answer Keep playing well and trust the long-run math
If decisions are sound, variance is the cause and results will recover over volume.