the measured angular diameter of the primary, after correction for limb darkening, is . at the estimated distance of upsilon draconis, this yields a physical size of about 19 times the sun's radius. it is about 1.37 billion years old with an estimated 2.05 times the mass of the sun. the star is radiating 2.23 times the solar luminosity from its photosphere at an effective temperature of 4,561 k.