17.

This is the normal age to graduate from secondary school, more or less the equivalent of your high school, at the middle level here. Broadly it’s like this; you go to primary school from 3 or 4 to twelve, in eight grades. Then you go through secondary school from 12 to either 16, 17 or 18 depending on your education level with the shortest being the lowest level. These levels allow follow-up education in three levels, among them higher education in the higher levels. Before primary education you can go to a pre-school, which I had to for a year I think.

I never repeated or skipped a class. I did take an extra year for graduating university.

So my track went like this; primary school until I was 12 > secondary school at the middle level until 17 > higher Bachelor education until 19 to be admitted to university > completed Bachelor education at 22 > Master’s degree until 25.

I was already 18 years and 6 months old when I graduated High School.

How can you write a Wikipedia-page worth content while the question was only about 1 number ?

18, almost 19, never repeated classes (in Italy, unless you start earlier, you enter high school in the year you turn 14, and unless repeating it lasts 5 years). One year I avoided repeating by a whisker, I had to pass September repair exams in Italian, History, Philosophy and Ancient Greek to be admitted to the fourth year. That Summer my late maternal granny, that studied Ancient Greek in high school and was the first of her class, revised it with me for the fifth time, after having done it with my uncle, my mom and my cousins. Back then she was 76 and she complained that, unlike in the past, she had to consult the dictionary every now and then.

I was 18 and never repeated a class. As for the last question I guess it depends on what you mean by feeling older. From a mutuality stand point no but from a educational stand point yes. This is my fault, I was young and immature and consider being around friends more important then my education so I made sure I was in the "regular classes" vs "honors classes" because that where all my friends at the time was at. The one time my parents made me take a more advance class I purposely did bad so that the teacher had me change to the regular class.

Thankfully it really did not harm me in college other then having to take Calculus one my first semester where most other computer science students started with Calculus two but other then that really had no effect on my time in college. That being said back in 2001 when I got into college it was a bit less competitive, having a High-school GPA in the high 3s was consider good unlike now where it gotten crazy and it almost expected at the better colleges you have an over 4 GPA (AP classes allow you to get over a 4 GPA)

16 years and 11 months, it hasn’t been 10 years since I graduated high school.

Born December’94 

graduated November ‘11 

Started school in ‘00

I graduated at 16. Turned 17 the month after graduating.

Read literally any sentence after the first one... 

"Also how many times did you repeat class ? did you feel 2 or 5 years older than other students certain classes ? If you dropped out you think you can comeback?" 

My bad for caring about the original post I guess. I was going to delete most of my answer anyways, but know that you've quoted it there's not really a point. 

18... never repeated a class, and finished pretty much at the age that is standard here.

Graduation was early October, so I was 17, one of the youngest. Most were fucking 18.