It is well known that many aluminium alloys attain optimum properties due to the formation of age-hardening precipitates, most of which are metastable from the thermodynamic point of view.Those age-hardening precipitates are often competed with and/or accompanied by a wide variety of non-hardening metastable precipitates as well as stable phases, which complicates the precipitation sequence.With the CALPHAD method, we systematically modelled the metastable precipitates as phases in the Al-Cu,Al-Cu-Mg, Al-Mg-Si and Al-Mg-Zn systems based on a critical review of experimental data and theoretical values, and incorporated them into TCAL, a multicomponent thermodynamic database for aluminium alloys of industrial relevance.The TCAL database can be used with software packages such as Thermo-Calc, DICTRA and TC-PRISMA.Selected calculation examples for different processes such as solidification, solutionization, aging etc., are presented to illustrate the application of TCAL (version 4) in the aluminium industry.For example, the formation of the metastable phase during the solidification simulation, stable phase equilibrium calculations for the analysis of solutionization, aging treatment and precipitation simulations of stable and metastable precipitates in aluminium alloys using the TC-PRISMA software, are demonstrated.From TC-PRISMA simulations, results of mean radius and number density of the precipitates are obtained and compared with experimental data.In addition, study of casting shrinkage and thixoformability using TCAL is presented as well.