The major factor that influences the cost is the size of the floor. The price per square foot will vary depending on regional labor costs, whether it is a residential or commercial space and if you will be refinishing stairs. In addition, a floor that is in good condition will typically have a lower cost per square foot than an older floor with heavy wear because it will need more preparation. Other factors that influence the overall cost include subfloor repairs or surface repairs that would need to be performed before the floor is refinished or if an old carpet has to be removed from on top of the hardwood floor.