Data from 191 size analyses of Recent sediments from several depositional environments were studied to obtain relationships among sediment size measures and sand-silt-clay composition. A simple analytical procedure exists whereby sediment size parameters of median, mean, deviation measure, and skewness of Recent sediments may be estimated from a three-component plot of sand, silt, and clay percentages. The three-component analysis is made easily by abbreviated size analysis methods, and the size parameters are obtained graphically from the three-component plot. Conversely, if the median and deviation measure of a sediment sample are known, the composition of the sediment may be obtained in terms of percent sand, silt, and clay. Thus, a one to one correspondence exists between points on the triangular diagram and pairs of median and deviation measure values (excluding the periphery of triangle). The estimation method for obtaining sediment size parameters will facilitate size analysis of large numbers of Recent sediment samples were semiquantitative data are desired.