Calculation of zakat who has savings but no earnings

Ãsak I would like to know is giving zakat compulsary for the person who is not earning but has little bit of savings. I used to had a job year ago but now I don't have any job but I had some savings left earned while I had a job. So I would like to know whether it is compulsory to give zakat in this situation and if yes how to calculate it?