Early-type galaxies (ETGs) are supposed to follow the virial relation M = ke2 Re=G, with M being the mass, being the stellar velocity dispersion, Re being the eective radius, G being Newton's constant, and ke being the virial factor, a geometry factor of order unity. Applying this relation to (a) the ATLAS3D sample of Cappellari et al. (2013) and (b) the sample of Saglia et al. (2016) gives ensemble- averaged factors hkei = 5:15 0:09 and hkei = 4:01 0:18, respectively, with the dierence arising from dierent denitions of eective velocity dispersions. The two datasets reveal a statistically signicant tilt of the empirical relation relative to the theoretical virial relation such that M / (2 Re)0:92. This tilt disappears when replacing Re with the semi-major axis of the projected half-light ellipse, a. All best-t scaling relations show zero intrinsic scatter, implying that the mass plane of ETGs is fully determined by the virial relation. Whenever a comparison is possible, my results are consistent with, and conrm, the results by Cappellari et al. (2013). The difference between the relations using either a or Re arises from a known lack of highly elliptical high-mass galaxies; this leads to a scaling (1-) / M0:12, with being the ellipticity and Re = a p 1 - . Accordingly, a, not Re, is the correct proxy for the scale radius of ETGs. By geometry, this implies that early-type galaxies are axisymmetric and oblate in general, in agreement with published results from modeling based on kinematics and light distributions.