A grease gun includes a housing, a motor positioned within the housing, a pump assembly coupled to and driven by the motor, and a chamber supported by the housing in fluid communication with the pump assembly. The chamber is configured to store a liquid. The grease gun also includes an outlet in fluid communication with the chamber and a measurement system operable to measure an amount of liquid being dispensed through the outlet. The measurement system monitors a change in current of the motor over a cycle of the pump assembly, compares the change in current to a predetermined value, and, if the change in current is greater than the predetermined value, increases a pump cycle counter to indicate that liquid was dispensed.