At what age does a girl start their period?

That can range anywhere from as early as eight years old to seventeen years old everyone is different but many girls experience theirs around the ages of twelve to fifteen.
The average age for a girl to start her period is 12 years old. Some start as early as the age of 7 it is not very common though. A girl can start her period between the ages of 7 - 16.
It can start anytime between 9-16 years of age, depending on weight and other factors. It is most common around 11-13.
at the age of 10-14 you should start your peiod normally girls start around that time