A Cosmology Calculator for the World Wide Web

A cosmology calculator that computes times and distances as a function of redshift for user‐defined cosmological parameters has been made available online. This paper gives the formulae used by the cosmology calculator and discusses some of its implementation. A version of the calculator that allows one to specify the equation‐of‐state parameter w and w′, and one for converting the light‐travel times usually given in the popular press into redshifts, is also located at the same site.