H-R diagram showing the location of our red-giant sample as directly determined from Eqs. (4) and (5) using the KIC effective temperatures (panel a)) and from the comparison with the stellar model grid (panel b) to e)). The colour code (in the online version only) indicates the stellar mass (a) and b)), radius c)), age d)), and metallicity (e)), where the radius scale has been truncated below 6 and above 14 R_⊙ . Grey lines show solar-metallicity BaSTI evolutionary tracks. The boxes given in the lower right corners illustrate typical uncertainties.