Size versus total cluster mass. Star and triangle symbols represent the f_b = 1 and f_* = 1 samples, respectively. The square, circle and diamond symbols represent a selection of local Universe data for GCs, young massive clusters and ultra-compact dwarfs, respectively, taken from the literature (see legend and text for further details). The dashed lines represent lines of constant density from 0.1m_h cm⁻³ − 10m_h cm⁻³ (from top left to bottom right).