As far as I know, Deidara is three years older than Naruto and the others, and two years older than Tenten, Neji and Xiao Li.
Deidara's younger Itachi is two years old and Itachi's younger Kakashi is nine, so Deidara's younger Kakashi is eleven years old.
Well... It's Jiang Zi...[Hey, hey! What are you talking about?
Ouch! I just want to say that the heroine Kakashi is twelve years old, Itachi is three years old, Tenten, Neji and Li are one year old, Naruto and the others are only two years old... Ugh... Cough cough, that is to say, the heroine is one year younger than Deidara.