29 CFR § 778.109 - The regular rate is an hourly rate.
The “regular rate” under the Act is a rate per hour. The Act does not require employers to compensate employees on an hourly rate basis; their earnings may be determined on a piece-rate, salary, commission, or other basis, but in such case the overtime compensation due to employees must be computed on the basis of the hourly rate derived therefrom and, therefore, it is necessary to compute the regular hourly rate of such employees during each workweek, with certain statutory exceptions discussed in §§ 778.400 through 778.421. The regular hourly rate of pay of an employee is determined by dividing his total remuneration for employment (except statutory exclusions) in any workweek by the total number of hours actually worked by him in that workweek for which such compensation was paid. The following sections give some examples of the proper method of determining the regular rate of pay in particular instances: (The maximum hours standard used in these examples is 40 hours in a workweek).