What age is The Perks of Being a Wallflower book for?

What age is The Perks of Being a Wallflower book for? Emma 13+ the book contains teenage and adult concepts. Julia Hörmayer I’d say around 14 and 16 years. Emma I think best stage of maturity for reading a heavy YA book like this would probably be “high school/14-18 years old”.

Is The Perks of Being a Wallflower book appropriate for a 13 year old? It’s not a bad book