Question Summary:
What should be the length and width of the turban(amamah)?

Question Detail:

What should be the length and width of the turban(amamah)?

Answer :

In the name of Allah, Most Gracious, Most Merciful
Assalaamu `alaykum waRahmatullahi Wabarakatoh
There is no reliable narration mentioning a specific length for the turban.  The sunnah of turban will be fulfilled with a cloth of any length.
And Allah knows best
Wassalam
Ml. Ehzaz Ajmeri,
Student Darul Iftaa
Concurred by:
Ml. Abu Yahya
Student Darul Iftaa
Darul Iftaa, Madrassah In'aamiyyah