How should you determine the value and comparables in your area. Say you live in a particular style home, then you should look at other homes in your neighborhood that area the same style. example: ranch = ranch, 2-story Colonial = 2-story Colonial, then a Cape Cod, Cape Cod = Cape cod, then 2-story Colonial. Try to get at least 3 similar comparables in style and similar in construction and close in square footage. Teh SF Price is the SP/SF. Remember don’t include basement space in this calculations. Only the SF that is above grade and finished. Basement SF is usually figured at a lesser value then above grade values and that is determined by similar features of other homes in the neighborhood.
If you are unsure what your square footage is or the value consult a REALTOR or call a local appraiser.