Harry's age

[Allison]

No: HPFGUIDX 20683

OK, I'm new so I don't know if this has been addressed or not; if it 
has, please don't kill me.

My question is about Harry's age.  His birthday is in July.  So is he 
older or younger then everyone else in his grade?  Hermione's 
birthday is in September, so she's either a few months younger or 
almost a year older.  

So, which is it?  I would guess JKR would make Harry a bit younger, 
but that's just me.  So if anyone knows, let me know.  Also, does it 
ever say in the books when Ron's birthday is?  Is he older or younger 
then Harry?

Thanks!
Allison