“Overtime refers to working hours beyond some standard or norm. For employees on payrolls, this standard is widely considered 40 hours, embodying the spirit of the Fair Labor Standards Act (FLSA) standard workweek.” (Golden)
“If the employee is employed solely on the basis of a single hourly rate, the hourly rate is his ‘regular rate.’ For his overtime work he must be paid, in addition to his straight time hourly earnings, a sum determined by multiplying one-half the hourly rate by the number of hours worked in excess of 40 in the week. Thus a $6 hourly rate will bring, for an employee who works 46 hours, a total weekly wage of $294 (46 hours at $6 plus 6 at $3). In other words, the employee is entitled to be paid an amount equal to $6 an hour for 40 hours and $9 an hour for the 6 hours of overtime, or a total of $294.” (U.S. Department of Labor)

Golden, L. (2003). Forced overtime in the land of the free. In J. de Graaf (Ed.), Take back your time (pp. 28-36). San Francisco: Berrett-Koehler Publishers, Inc. U.S.Department of Labor. (1981). Code of federal regulations for the U.S. Department of Labor: 29 CFR 778.110 - Hourly rate employee. Retrieved on December 6, 2005.