As per this question and the Naruto wikia, Naruto was 12 at the start of the show. The Naruto wikia also lists Sasuke and Sakura as being 12 at the start, which indicates that they're the same age. It's also corroborated by this, which says it got it from the Official Character Stats Book.
As you point out, it's not really clear how that works out, given that he's stated to have failed the exam to become a genin more than once (I'm assuming that's what you're asking about, rather than the Chunin exam, given context). Possibilities for that include either that he started younger or that it's just a timeline mess that they never bothered to deal with. I'm guessing the latter.