Poker variance calculator
Even a winning player can lose over thousands of hands. Enter your win rate and standard deviation (both in big blinds per 100 hands) and a number of hands, and the calculator shows your expected result, the range where 95% of results land, the chance of being down and how big a typical downswing is.
Your average result per 100 hands. Use a negative number for a losing win rate.
How much your results swing per 100 hands. PokerCraft and other stats tools can show yours; if unsure, try a few values.
Results are in big blinds (bb), the same in any game or stake. Chips on ClubGG have no monetary value.
- Expected result
- +2,500 bb
- Chance you’re down
- 10.7%
- after 50,000 hands
- Typical downswing
- 1,514 bb
- median of 1,000 runs
- Bad downswing
- 2,917 bb
- 1 run in 20 is worse
20 possible ways it could go
Green: expected result. Shaded: where 95% of results should land (−1,444 bb to +6,444 bb). Grey and red lines: simulated runs. Dashed: break-even.
- Most likely range (68% of results)
- +488 bb
- to +4,512 bb
- Hands to be 95% sure you’re winning
- 124,468
- if your true win rate is this one
For study and hand review only. Don’t use outside tools during live play. Many poker apps, including ClubGG, restrict real-time assistance. Results are estimates for learning.
The maths
Over N hands, your expected result is win rate × N ÷ 100 and the spread is standard deviation × √(N ÷ 100). About 68% of results fall within one spread of the expectation and about 95% within 1.96 spreads. The chance of being down uses the normal distribution.
Downswings come from 1,000 simulated runs: for each run the calculator records the biggest drop from a high point, then reports the median and the run that is worse than 19 in 20.
What to take from it
Short samples tell you very little. If your standard deviation is large compared with your win rate, it can take hundreds of thousands of hands to be confident you are a winning player. Judge decisions, not short-term results, and play stakes your bankroll can absorb.
Frequently asked questions
What is standard deviation in poker?
A measure of how much your results swing per 100 hands. Higher means bigger swings. Stats tools such as PokerCraft can show yours.
What is bb/100?
Big blinds won or lost per 100 hands. It lets you compare results across different blind levels.
How many hands do I need to know my win rate?
Usually far more than people expect. With a win rate of 5 bb/100 and a standard deviation of 90, you need roughly 125,000 hands before a 95% interval stays above zero.
Can a winning player lose over 10,000 hands?
Yes. Short samples are dominated by luck. The calculator shows how often that happens for your numbers.