A dispense control system for filling a container using a dispensing assembly of a refrigerator appliance and a method for operating the same are provided. The dispense control system includes an emitter for generating a beam of energy and a scanning assembly for selectively directing the beam of energy along a scan path comprising a plurality of scan positions. A receiver detects the beam of energy reflected by the container or the liquid at each of the plurality of scan positions and a controller determines a height of the container or the liquid at each of the plurality of scan positions along the scan path based at least in part on a travel time of the beam of energy between the emitter and the receiver.