Hostel Cost structure/Major Cost items

Hello All,
I am new to the forum, it seems to include a ton of operation information which is great!
I am also looking at how hostel finances generally look like. Right now it's most for academic reasons but hopefully in the future it will help me in deciding on starting a hostel.

What are the major cost items in a hostel?
Could you share how they break down (Percentage wise or however you feel like sharing)
If possible mention the approximate size of the hostel and the type of city to help me make the correct comparison. [Hostels in NYC probably pay much more in rent than ones in Hanoi I guess!]

Thank you very much for your help!

Best,

Louis