It all depends on the size of the hide and how much you are going to do.
Some leather is thinner than other parts and with that in mind, you will most likely need three to four hides to cover what you said.
It is not just surface area, but the grade of the leather to what is being covered. Very thin material will rip over time and very thick stuff is too hard to work with.
Do you have cows you are going to butcher to get the hide?
