The calculator takes all cost inputs and divides them by the hours spent working (extracting holidays, medical leaves etc.). The results represent monetary cost of man-hour and man-month worked.
Typical gross wage information does not reveal the real cost of employing people. It does not account for all monetary cost included (like meal vouchers) and more importantly, it does not account for time worked. Real cost of employment can be thus influenced by legislation not directly affecting wages, like worktime regulation.