The average age to start menstruation in the US is 11-12. There are several reasons a girl may start later. Athletes, dancers and very thin girls tend to start later. It may not be a bad idea to take her in to the dr and get a physical just to rule out anything else.
Like what most people are saying, 12 or 13. I got started mine a few months before I turned 13. But it's not the same with everyone.
A girl usually starts her period at the age of 12 but that doesnt mean that all girls will have their period at the same age.
At the age of 12 or 13 which depends
Well most girls get their periods at 12 or 13, some get them at 9 (early) or 15 (late). All are normal.
I got mine when I was 11 but don't sweat it. The time is going to come
I am 11 1/2 and when should I start my period??
I don't know, usually they start from 10 to 13 or 14 so I do not think you should worry that much, but I would see a doctor just in case