Age-luminosity relations for low-mass metal-poor stars

We present a grid of evolutionary calculations for metal-poor low-mass star s for a variety of initial helium and metal abundances. The intention is ma inly to provide a database for deriving directly stellar ages of halo and g lobular cluster stars for which basic stellar parameters are known. but the tracks can also be used for isochrone or luminosity function construction, since they extend to the tip of the red giant branch. Fitting formulae for age-luminosity relations are provided as well. The uncertainties of the ev olutionary ages due to inherent shortcomings in the models and due to the u nclear effectiveness of diffusion are discussed. A first application to fie ld single stars is presented.