The U.S. Department of Labor has a great website advising both employers and employees in the area of overtime pay. The FLSA Overtime Calculator Advisor provides information and links to guide you.
Here’s a snip-it from their introduction page: The Fair Labor Standards Act (FLSA) requires that covered, nonexempt employees in the United States be paid at least the federal minimum wage for each hour worked and receive overtime pay at one and one-half times the employee’s regular rate of pay for all hours worked over 40 in a workweek. FLSA overtime pay is due on the regular pay day for the period in which the overtime was worked. The overtime pay requirement may not be waived by agreement between the employer and the employee. The overtime pay requirement cannot be met through the use of compensatory time off (comp time) except under special circumstances applicable only to state and local government employees.