In a system and a method for calibrating turn-on energy of a fluid-ejecting marking device, a reference object and a plurality of test objects are contemporaneously printed by the marking device on a same type of substrate. The reference object is printed at a known 'on' voltage at a first pattern density, and the test objects are printed at a series of decrementing voltages at an intended secondpattern density greater than the first pattern density. A scanning device compares the reference object to the test objects to determine which test object(s) most closely resemble(s) the reference object. Based at least upon this comparison, a turn-on energy for the marking device is determined. By using a reference object to compare the test objects to, a turn-on energy can be calculated independent of the type of substrate used and the ambient conditions present when printing the reference and test objects.