The m1 scale has been defined (Chen and Atkinson, 2002) in the frequency domain, where the Fourier acceleration amplitude at 1 Hz is employed. The mhf and Mlp magnitude scales are determined accordingly with the high-frequency acceleration spectrum and the low-frequency displacement spectrum, respectively. This article deals with the similarity and correlations of these new magnitude scales with the popularly used moment magnitude (M) and the magnitude scales defined in the time domain, such as mb, MS, and ML, among others. The magnitudes m1, mhf, and Mlp are associated with intermediate-, high-, and low-frequency bands, respectively, estimated from spectra corrected for geometric and anelastic scattering effects. Comparisons between the magnitude scales demonstrate that m1 is a reliable indicator of earthquake size, which is not only well correlated with the local or regional magnitude but also is a good measure of the moment magnitude for at least small-to-moderate earthquakes.