Okay. So everyone who's read Goblet of Fire knows that Hermione went to the Yule Ball with Viktor Krum. He seemed rather interested in her, and not just in a "friend" kind of way.
So why does everyone seem to think she's younger than her classmates? Come on. I'm all for disparate ages in romantic relationships, but a 14-year-old and a 17-year-old? No. Just... no. That, I find creepy.
Hermione is older than the rest of her class. She was born on September 19th, just after the cutoff for her age group (September 1st). This would make her fifteen in Goblet of Fire, and a year older than the rest of her class.
Not to mention, even if we ignore pure canon and go into secondary canon, Jo Rowling explicitly states that Hermione was almost twelve when she started Hogwarts, not almost eleven.
*sigh* Okay. I feel better.