An important function of drilling mud is the control of formation fluid pressure to prevent blowouts. The density of the mud must be raised at times to stabilize incompetent formations. Any substance that is denser than water and that does not adversely affect other properties of the mud can be added to raise the density to some extent. Obviously, the specific gravity of the weighting agent is of primary importance, especially in very heavy muds. The fractional volume occupied by the added solid is a major limiting factor in its use. In this work a simple-to-use correlation has been developed to predict the effect of the specific gravity of the weighting material and the density of mud on the solids concentration of weighted muds. Estimations are found to be in excellent agreement with the reliable data in the literature with average absolute deviation being less than 0.3%.