The Relationship Between Neutrinos and the Big Bang

Our models of the Big Bang tell us that there were a lot of neutrinos at the Big Bang and that they have mass. So we know something about how many neutrinos there were. We could put an upper limit on how massive they could be without collapsing the universe. That number is less than the 10th of an electron volt, which I guess to give us some context, how much mass is an electron have?