Abstract The Ca–Ag binary system has been assessed with CALPHAD approach based on experiment information about phase diagram and thermodynamic properties. The excess Gibbs energies of the solution phases including liquid, bcc and fcc were formulated with Redlich–Kister polynomial functions. The intermetallic compounds Ca 2Ag 9, Ca 2Ag 7, CaAg 2, CaAg, Ca 5Ag 3 and Ca 3Ag were treated as stoichiometric phases. Self-consistent thermodynamic parameters have been obtained and the calculated results agree well with most literature data. Several diagrams and tables concerning the Ca–Ag system are presented.