A neuromodulation system configured for providing sub-threshold neuromodulation therapy to a patient. The neuromodulation system comprises a neuromodulation lead having at least one electrode configured for being implanted along a spinal cord of a patient, a plurality of electrical terminals configured for being respectively coupled to the at least one electrode, modulation output circuitry configured for delivering sub-threshold modulation energy to active ones of the at least one electrode, and control/processing circuitry configured for selecting a percentage from a plurality of percentages based on a known longitudinal location of the neuromodulation lead relative to the spinal cord, computing an amplitude value as a function of the selected percentage, and controlling the modulation output circuitry to deliver sub-threshold modulation energy to the patient at the computed amplitude value.