What type of area is it? Is it located in the basement? Or above grade, in the main living areas? What needs to be finished? Let your potential buyers know everything upfront. If it's unfinished area above ground you will face difficulties when the potential buyer needs to obtain financing.
Banks and Lenders do not like unfinished areas above grade! With exception of attic space or lofts that are sectioned off from the main areas of living.
Call me with any questions! Jared Anderson @ 801-999-0201. As a Certified Appraiser and Real Estate Agent I deal with these kinds of issues on a daily basis!
Here in Utah we list total square footage whether it is finished or not.
In other states, they only list main floor square footage.
This is information your agent can easily get for you.