How do you calculate overtime man-hours?

To calculate overtime man-hours, first determine the total hours worked by an employee in a given pay period. Subtract the standard hours (usually 40 hours per week in the U.S.) from the total hours worked to find the overtime hours. Multiply the overtime hours by the number of employees working those hours to find total overtime man-hours. For example, if two employees worked 10 hours of overtime, the total overtime man-hours would be 20 hours (2 employees x 10 hours).