This measurement is typically made for a standard reporting period, such as a month, quarter, or year.
The net profit margin is intended to be a measure of the overall success of a business. A high net profit margin indicates that a business is pricing its products correctly and is exercising good cost control. It is useful for comparing the results of businesses within the same industry, since they are all subject to the same business environment and customer base, and may have approximately the same cost structures.