The conversion of cubic meters per day to quart per second is a unit conversion that represents the rate of flow or volume of a substance in different measurement systems. Cubic meters per day (m³/day) is a unit of volume flow rate commonly used in engineering and scientific applications, while quart per second (qt/s) is a unit of volume flow rate used in the United States customary system. To convert cubic meters per day to quart per second, one must multiply the given value by 0.000016387064, as there are 1,728 cubic inches in a cubic foot, 46,656 cubic inches in a cubic meter, and 57.75 cubic inches in a quart. This conversion is essential in various fields, including hydrology, where it is used to measure the flow rate of rivers and streams, and in chemical engineering, where it is used to calculate the rate of fluid flow in pipelines and reactors.