This document describes a test method for determining the particle density by the pycnometer method within the scope of the geotechnical investigations according to prEN 1997-1 and prEN 1997-2. The pycnometer method is based on the determination of the volume of a known mass of soil by the fluid displacement method. The density of solid particles is calculated from the mass of the soil and the volume. The pycnometer method applies to soil types with particle sizes under 4 mm.