A man-hour is the amount of work performed by the average worker in one hour. It is used for estimation of the total amount of uninterrupted labour required to perform a task. For example, researching and writing a college paper might require eighty man-hours, while preparing a family banquet from scratch might require ten man-hours. A man-hour is the amount of work performed by the average worker in one hour. It is used for estimation of the total amount of uninterrupted labour required to perform a task. For example, researching and writing a college paper might require eighty man-hours, while preparing a family banquet from scratch might require ten man-hours.