Size and time are functionally related to scale of shore erosion by $$S = f(A_{e}, T_{e}$$), where S is the scale, $$A_{e}$$ the equilibrium amplitude, and $$T_{e}$$ the equilibrium time. Equilibrium amplitude is the vertical variation of profile translation required to restore equilibrium; equilibrium time is the period required. Scales in shore erosion are designated as: (1) microscale, representing the swash-backwash zone (mean vertical variation $$10^{1} cm.$$, mean period $$10^{1} min.$$); (2) macroscale, representing neap-spring or seasonal cycles (mean vertical variation 102 cm., mean period $$10^{4}+10^{5} min.$$); (3) megascale, representing long-term changes in sea level (vertical variation on the order of $$10^{3}-10^{4} cm.$$, period $$10^{9}-10^{10} min.$$). The correlation between the equilibrium amplitude and the equilibrium time suggests the universality of the Bruun effect.