A JavaScript Passive Evolution Calculator

We present a JavaScript calculator which provides the redshift evolution of the luminosities and colors of passively evolving galaxies for a range of rest-frame filters. In its simplest form it gives the evolution of a single age stellar population formed at a given redshift. However, it can also incorporate morphological evolution in the galaxy population ("progenitor bias") and complex star formation histories of individual galaxies. The calculator is based on the models of van Dokkum & Franx (2001), with small updates.