A modular hopper assembly for use with a seed meter of a row unit for an agricultural planter is provided. The modular hopper assembly includes a base hopper unit that can be attached to the row unit. The base hopper unit can be attached to a seed delivery apparatus, such as an air seed delivery of a central hopper. The base hopper unit is also configured to be attachable to various sizes of row hoppers that can quickly and easily attach to the base unit to provide for varying amounts of storage at each of the row units. As the base unit is operatively attachable to a seed meter, the base unit can be used with generally any seed delivery device, including row hoppers, fluid seed deliveries connected to central hoppers, or the like.