question for a math whiz

[2283]

sorry if this should be in the probability formum.

question is: how accurate is a win rate after, say, 12,000 hands? assuming i'm a relatively tight player, can someone give me an approximate range that contains my "true" win rate expectation to some degree of probability? (eg, "there's a 90% chance your very long-term win rate is within 15% of your win rate after 12000 hands.") just curious. rough guesses are welcomed.