Abstract: An apparatus and method are provided for optical liquid level determination in a liquid dispensing system. Accurate volume dispensing based on the level determination is also provided. An optical sensor device emits a light signal downward into the tank toward the liquid, and received a portion of the light signal that has been reflected upwardly by a surface at the top of the liquid. A processing system calculates the height of the liquid in the tank based on a time of flight measurement of the light signal. A head pressure of the liquid over a controllable dispensing valve located at the bottom of tank may then be calculated using the calculated height of the liquid in the tank. An open time for the controllable dispensing valve is then calculated, based on the calculated head pressure, in order to dispense a predetermined volume of liquid from the tank.