Abstract A complete map of the youngest stellar populations of the Milky Way in the era of all-sky surveys is one of the most challenging goals in modern astrophysics. The characterization of the youngest stellar components is crucial not only for a global overview of the Milky Way’s structure, of the Galactic thin disk, and its spiral arms, but also for local studies. In fact, the identification of star-forming regions (SFRs) and the comparison with the environment in which they form are also fundamental to put SFRs in the context of the surrounding giant molecular clouds and to understand still unknown physical mechanisms related to star and planet formation processes. In 10 yr of observations, the Vera C. Rubin Legacy Survey of Space and Time (Rubin LSST) will achieve an exquisite photometric depth that will allow us to significantly extend the volume within which we will be able to discover new SFRs and to enlarge the region of our own Galaxy we have detailed knowledge about. We describe here a metric that estimates the total number of young stars with ages t < 10 Myr and masses >0.3 M ⊙ that will be detected with the Rubin LSST observations in the gri bands at a 5 σ magnitude significance. We examine the results of our metric adopting the most recent simulated Rubin LSST survey strategies in order to evaluate the impact that different observing strategies might have on our science case.