Methods and systems for determining acidizing fluid injection rates for stimulation of a subterranean formation arc provided. In one embodiment, methods comprise: selecting a first injection rate for injecting an acidizing fluid into a subterranean formation; calculating a first objective function based on the first injection rate; selecting a second injection rate for injecting the acidizing fluid into the subterranean formation; calculating a second objective function based on the second injection rate; comparing the second objective function with the first objective function to determine whether the second objective function is indicative of more effective stimulation, less effective stimulation, or the same stimulation as the first objective function; and selecting a design rate for injecting the acidizing fluid into the subterranean formation.