Gallons and cubic feet measure volume, while minutes and seconds measure time. When you measure units of volume per unit of time, you get flow rates such as cubic feet per second or gallons per minute. When converting between flow rates, you can either do it in two steps -- first the units of volume and then the units of time -- or in one shorter step that combines the two conversion factors.
Multiply the number of cubic feet per second by 7.4805 to convert to gallons per second. For example, if you start with 42 cubic feet per second, multiply 42 by 7.4805 to get 314.181 gallons per second.
Multiply the number of gallons per second by 60 to convert to gallons per minute. In this example, multiply 314.181 by 60 to get 18,850.86 gallons per minute.
Multiply the number of cubic feet per second by 448.83 to convert directly from cubic feet per second to gallons per minute. In the example, check your answer by multiplying 42 by 448.83 to get 18,850.86 gallons per minute.