A method of confirming volume during dispensing of a liquid using pressure. The method includes attempting to dispense a volume of the liquid from a dispense port, measuring a pressure associated with the attempted dispense of the liquid and providing a measured pressure signal, determining a liquid dispensing start time and a stop time based on a slope of the measured pressure signal, integrating the measured pressure signal between the start time and the stop time to provide an integrated pressure value, and comparing the integrated pressure value to one or more preset threshold values. Liquid dispensing apparatus are provided, as are other aspects.