Standard Deviation in Poker: The Number That Decides How Long You Wait
Most players never look at this number, and it's the one that decides how much of their results are real. Your win rate is a signal. Standard deviation is the noise it has to be heard over.
What the number means
Your win rate is an average. Standard deviation is how far from that average an ordinary stretch lands.
Both are measured the same way, in big blinds per hundred hands, which makes them directly comparable. That comparison is the whole point.
Say you win at 5bb/100 with a standard deviation of 90. Over the next hundred hands, the average outcome is plus five big blinds and the ordinary range runs from about minus 85 to plus 95.
Read that again. The noise is eighteen times the signal. Not over a career, but over any hundred hands you actually sit down and play.
Typical figures
| Game | Standard deviation, bb/100 |
|---|---|
| Six-handed online Hold'em | 90 to 100 |
| Full ring online Hold'em | 75 to 85 |
| Fast-fold pools | 95 to 110 |
| Live Hold'em | 90 to 120 |
| Pot-limit Omaha | 130 to 180 |
Use your own rather than one of these. Every tracker reports it beside your win rate, and the spread between players in the same game is wide enough that a typical figure will mislead you.
Omaha's row explains a lot about how that game feels. The swings aren't in your head, they're roughly twice the size.
What it's actually for
Standard deviation on its own is a curiosity. Paired with your sample, it answers the only question that matters about your results: how much of this is real?
The uncertainty around your measured win rate is your standard deviation divided by the square root of your sample in hundreds of hands.
With a standard deviation of 90:
| Hands played | Uncertainty around your win rate |
|---|---|
| 10,000 | About 9bb/100 |
| 50,000 | About 4bb/100 |
| 100,000 | About 2.8bb/100 |
| 500,000 | About 1.3bb/100 |
Take the 100,000 row. You've measured 4bb/100, and the true figure is plausibly anywhere from roughly 1.2 to 6.8 once you allow the ordinary margin either side. Widen it to the range you'd want before betting your life on it and the bottom end goes negative.
That's a hundred thousand hands. Most players never get there in a year.
The part that hurts
Notice the square root in that formula. It means the returns diminish hard.
Going from 10,000 hands to 40,000 hands does not halve your uncertainty twice. It halves it once. To halve it again you need 160,000.
So there's no amount of ordinary play that makes your win rate precise. This isn't a reason to despair, it's a reason to stop reading results week to week and use the stats that settle faster. VPIP and PFR are meaningful in a thousand hands because you make those decisions constantly.
High swings aren't a fault
There's a temptation to treat a high standard deviation as something to fix. Usually it shouldn't be.
The styles that produce the biggest swings, playing more hands and building bigger pots, are frequently the same ones that produce the biggest win rates. Cutting your swings by tightening up often cuts your earnings by more.
What a high standard deviation genuinely demands is a bigger bankroll. That's the honest trade: you can play a wilder style, and you have to be funded for it. The bankroll guide covers the sizing.
How to use it this week
Pull two numbers out of your tracker: your win rate and your standard deviation. Then feed both into the variance calculator along with your sample.
What comes back is the range your results could reasonably sit in, and usually the surprise is how wide it is. A losing stretch you'd been treating as evidence of a leak often turns out to be inside the ordinary band.
That's worth knowing before you rebuild your game around a bad month. For the other half of the question, what the win rate itself should look like, see the win rate page.
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Frequently asked questions
What does standard deviation measure in poker?
How much your results bounce around, in big blinds per hundred hands. A standard deviation of 90 means an ordinary hundred-hand stretch lands somewhere within about 90 big blinds either side of your average, and stretches well outside that are perfectly normal.
What is a typical standard deviation?
Around 90 to 100 big blinds per hundred hands for six-handed online Hold'em. Full ring runs lower, near 75 to 85, because you play fewer hands. Pot-limit Omaha is far higher, often 130 to 180, which is why it feels so much wilder.
Is a high standard deviation bad?
No, and it often comes with a higher win rate. Playing more hands and more aggressively creates bigger swings and more profit at the same time. It only becomes a problem when your bankroll isn't sized for it.
How do I find my own standard deviation?
Every tracker reports it, usually on the same screen as your win rate. Use your own rather than a typical figure, because it varies by a wide margin between players and it's the input to every calculation on this page.
How does standard deviation affect how many hands I need?
Directly. The uncertainty around your win rate is your standard deviation divided by the square root of your sample in hundreds of hands. Double the standard deviation and you need four times the hands to reach the same confidence.
Why is my standard deviation higher than a friend's?
Usually style. Wider preflop ranges, more 3-betting and more big pots all push it up. Table size and stakes matter too. It's a description of how you play rather than a measure of how well.
Does standard deviation tell me how big my downswings will be?
Partly, and it's the main input. A downswing of several times your standard deviation is ordinary over a career. This is why a variance calculator asks for it before it will tell you anything useful.