Characteristic stellar mass buildup timescale normalized by the age of the Universe of τ_h = 13.8 Gyr (Planck Collaboration XIII 2016) in dependence of the stellar mass in the invariant canonical IMF (left panel) and the IGIMF-2021 (right panel) context for galaxies located in the LV. The dashed red line refers to a characteristic stellar mass buildup timescale equal to τ_h = 13.8 Gyr. In the right panel, the uncertainty of the IGIMF effect is plotted while the measurement errors are not shown. The upper and lower limits of the IGIMF-corrected τ_⋆ values (right panel) are estimated by adopting τ_up, ⋆ = M_upper, ⋆/ψ([Z] = −2.20) and τ_low, ⋆ = M_low, ⋆/ψ([Z] = 0.45), respectively. ψ([Z] = −2.20) and ψ([Z] = 0.45) refer to the IGIMF-corrected SFR values for [Z] = −2.20 and [Z] = 0.45 (Sect. 4.2). M_up, ⋆ and M_low, ⋆ refer to the upper and lower IGIMF-corrected stellar masses by applying the maximum and minimum M_⋆/L_K values (Sect. 4.2). The solid red lines are fits of the data with Eq. (23).