[pzhon]

I'm surprised that there were so many useless and incorrect answers.

You need to know your standard deviation, say per 100 hands. In NL, this depends more on your playing style than in limit, but typical figures are about 85 big blinds/100 in full ring and 95 big blinds/100 in 6-max. The latter is more sensitive to playing style than the former. PokerTracker reports an estimate of your standard deviation under Session Notes->More Details.

In case you meant limit hold'em, the standard deviation is usually about 15 big bets/100 in full ring, and about 17 big bets/100 shorthanded.

After n * 100 hands, the standard deviation of your win rate is (SD per 100)/sqrt(n). After 10,000 hands, n=100, so this would be (SD per 100)/10. A rough 95% confidence interval is the observed rate +- 2 standard deviations.

I'll let you decide whether your BB/100 was big blinds/100 or PTBB/100, and determine your standard deviation.