Sand-soil mixtures are commonly used in drained turf sites such as golf greens and athletic fields to ensure adequate soil strength, minimum compaction, and corresponding suitable water retention and infiltrability. The physical properties of the components vary significantly from site to site and mixture proportions must be adjusted to compensate for this. This adjustment usually involves empirical testing of various mixtures of the components to determine the correct proportions to use. One objective of this project is to develop a simple, applied method useful in the prediction of mixture porosity and water retention, which might eliminate or at least significantly reduce empirical testing. A graphical method based on component bulk volume proportions and which requires knowledge of the component porosities was developed and demonstrated to accurately predict water retention porosity, aeration porosity, and total porosity in sand-soil mixtures. This method, described herein, should prove of practical use in determining correct mixtures of sand and soil for drained turf sites.