The throughput advantage associated with Fourier-transform spectrometers is examined in the context of imaging spectrometers. The imaging throughput advantage is found to be inversely proportional to the number of spatial- resolution elements in the image cube. That number is also known as the space-bandwidth product and indicates an imager's information-collection capability. In the limit of one spatial resolution element, the advantage expression derived here reduces to the formulation presented elsewhere in the literature. A simple expression for the imaging- throughput advantage is also derived for the case of diffraction-limited imaging.