The dynamic behavior of coastal structures under wave impact closely depends on the temporal and spatial variations of the impact load. The dynamic analyses and design of a coastal structure succeeds if the design load history for the wave impact is available. Since these types of data are very difficult to find, it is more proper to use a method based on static analysis. For this purpose, the ratio of the maximum value of the dynamic response to that found by static analysis is presented as a factor of multiplication and is called ''dynamic magnification factor.'' The dynamic magnification factors from waves breaking directly on vertical coastal plates with built-in edges are calculated for different thicknesses and aspect ratios. The governing equation of the problem is solved by finite element method in which a mesh dependency study is carried out for each plate to find the most appropriate mesh density. From the present computational results, it is suggested that the bending moments from the static analysis of plates can be modified by a factor of 1.15 to obtain the equivalent dynamic bending moments for the plate dimensions in the range of 0.8 <= a/b <= 3 and the wave condition considered in the study.