Spectrally-disjoint radar waveforms seek to minimize the amount of energy in a set of frequency bands within the bandwidth of the waveform. Such a waveform will suffer higher range sidelobes than a waveform with a contiguous bandwidth. As we continue to develop these waveforms, it becomes necessary to establish peak sidelobe level ratio (PSLR) and integrated sidelobe level ratio (ISLR) predictions in order to objectively evaluate performance. In this paper, we derive a closed-form prediction for PSLR and ISLR. These predictions provide sidelobe estimates as a function of usable bandwidth. Predictions such as these can aid in the decision making process of an adaptive radar.