Due to Varuna's ellipsoidal shape, multiple observations have provided different estimates for its diameter, ranging from . Most diameter estimates for Varuna were determined by measuring its thermal emission, although size estimates have been constrained to smaller values as a result of higher albedos determined by space-based thermal measurements. Observations of stellar occultations by Varuna have also provided varying size estimates. An occultation by Varuna in February 2010 yielded a chord length of , inferred to be across its longest axis. Later occultations in 2013 and 2014 yielded mean diameters of and respectively.