Abstract: Disclosed are a method and a device for determining characteristics of particles dispersed in gases and liquids in the nano- and microscale size ranges and the number distribution and concentration thereof by use of particle photometry. This can be achieved by producing scattered light measurements in a photometer for a different number of aperture or receiving angles and evaluating particle characteristics from the determined scattered light intensities using evaluation algorithms. The determination of particle characteristics over a size range of several decades is made possible without the need to change or adapt the geometry of the sample measurement chamber.