The Volume-Mass Calculator is an app for calculating the basic geotechnical properties of soil including parameters such as specific gravity, water or solids content, density, unit weight, porosity, void ratio, volumetric water content, and degree of saturation. The Volume-Mass Calculator has been programmed based on standard phase relationships and calculates the full suite of properties if three of the parameters are known. The slider feature allows the user to adjust the three known parameters to observe and gain a better understanding of the relationship between the properties. The calculator includes settings to switch between metric and imperial units, and set the governing pore fluid density. A must have tool for anyone in the field of geotechnical engineering.