Reference position of the benchmark stars used in this study in the log g-T_eff plane. Colour coding for literature values: Smith & Dworetsky (1993, yellow), Lefever et al. (2010, magenta), Simón-Díaz et al. (2006, green), Simón-Díaz (2010, dark green), Nieva & Simón-Díaz (2011, cyan), Nieva & Przybilla (2012, blue), Mokiem et al. (2005, sienna), Morel & Butler (2008, red), Hubrig et al. (2008, red), and Martins et al. (2012, orange). The average, adopted parameters are shown as a black cross. Evolutionary tracks at solar metallicity and with ω_init = 0.568 are overlaid (Ekström et al. 2012). The initial stellar mass (in solar units) is indicated.