Vases have continued to be important aesthetic objects across almost all developed cultures. Still, there is few to no systematic research investigating the shape properties that determine their beauty. A famous exception is Birkhoff (1933), who used the geometric relations of vases for calculating their beauty. However, one shape factor he theoretically considered, but did not include in his aesthetic measure is the outline curvature of vases. Already in 1753, William Hogarth emphasized curvature as relevant for aesthetic appreciation, when he introduced his “Line of Beauty” as the most beautiful shape. Given the influence of both theories it is astonishing that empirical investigation is lacking. Therefore, we produced 25 symbolic vases, where we systematically varied width and curvature and asked participants to rate their beauty in an online experiment. Multiple regression results show that both geometric relationships and curvature contribute to the beauty of vases.