How do you know if you're bi?

If you try sexual things with a girl, and then you find that you hope to do it again, then you possible are bi-sexual.

Are you attracted to both men and women? Have you had sexual relations with both sexes?

Its actually a mind thing, if you think intimate of both guys AND girls then you might be bisexual. Sometimes its just curiosity, you can tell that if you really want a girl but don't wanna be with her.

If you want to be BI then your bi. Sexuality is something you chose whether it's straight, gay, lesbian or bi.