The paper addresses the issue of improving the age estimation for solar-type dwarfs using chromospheric activity diagnostics. The authors compiled $R'_{HK}$ data from the literature for young stellar clusters, which is the first time such data has been used to populate the young end of the activity-age relation. By combining cluster activity data with modern cluster age estimates and analyzing the color dependence of the chromospheric activity age index, they derive an improved activity-age calibration for F7-K2 dwarfs ($0.5 < B-V < 0.9$ mag). They also present a more fundamentally motivated calibration that relies on converting $R'_{HK}$ values through the Rossby number to rotation periods and then using improved gyrochronology relations. The new activity-age calibration has a typical age precision of $\sim 0.2$ dex for normal solar-type dwarfs aged between the Hyades and the Sun ($\sim 0.6$-4.5 Gyr). The authors demonstrate that coronal activity, measured through the fractional X-ray luminosity ($R_X = L_X/L_{bol}$), has nearly the same age- and rotation-infering capability as chromospheric activity measured through $R'_{HK}$. As a first application of their calibrations, they provide new activity-derived age estimates for the nearest 100 solar-type field dwarfs ($d < 15$ pc).The paper addresses the issue of improving the age estimation for solar-type dwarfs using chromospheric activity diagnostics. The authors compiled $R'_{HK}$ data from the literature for young stellar clusters, which is the first time such data has been used to populate the young end of the activity-age relation. By combining cluster activity data with modern cluster age estimates and analyzing the color dependence of the chromospheric activity age index, they derive an improved activity-age calibration for F7-K2 dwarfs ($0.5 < B-V < 0.9$ mag). They also present a more fundamentally motivated calibration that relies on converting $R'_{HK}$ values through the Rossby number to rotation periods and then using improved gyrochronology relations. The new activity-age calibration has a typical age precision of $\sim 0.2$ dex for normal solar-type dwarfs aged between the Hyades and the Sun ($\sim 0.6$-4.5 Gyr). The authors demonstrate that coronal activity, measured through the fractional X-ray luminosity ($R_X = L_X/L_{bol}$), has nearly the same age- and rotation-infering capability as chromospheric activity measured through $R'_{HK}$. As a first application of their calibrations, they provide new activity-derived age estimates for the nearest 100 solar-type field dwarfs ($d < 15$ pc).