Physical and aerodynamic characteristics of several refuse derived fuel (RDF) samples were studied. Each RDF sample was tested in a wind sieve to classify the particles into different fractions according to their terminal velocity. The individual particles from the wind sieve were then manually separated according to the material type and physically characterized by weight measurement and 2D photographing. For the tested samples, despite the overall weight distribution of the fractions from the wind sieve being similar, the material distribution of particles in each fraction was significantly different. It has been shown that, regardless of the particle material, for each group of particles from the wind sieve test, the ratio of particle maximum projected area to particle mass lies in a narrow range. A new approach based on the particle maximum projected area was proposed to predict the terminal velocity of particles and was tested for each group of particles from the wind sieve experiment. The maximum deviation of the mass-based averaged terminal velocity predicted from the drag model compared to the mid-point wind sieve velocity was smaller than 14%. A procedure was proposed for physical characterization of RDF particles based on the wind sieve test and 2D imaging of particles. This characterization can be used as an input for computational fluid dynamics (CFD) calculations of RDF-fired cement calciners and rotary kilns.