Computing Regular Rate of Pay - Salaried Employee Working More Than 40 Hours a Week
If an employee receives a salary for all hours worked, then the regular rate varies according to the number of hours worked in a week. The employee’s regular rate is determined by dividing the weekly salary and other forms of compensation by the number of hours worked.29 C.F.R. § 778.114.

Example:
If an employee works 50 hours for a weekly salary of $500, the regular rate is $10 an hour. Overtime for this employee is based on half-time and would be $5 an hour for 10 hours, which is $50. The regular rate of an employee who is paid a salary for all hours worked varies each week depending on the hours actually worked.