The latest results of inclusive and differential $t\bar{t}$ cross-section measurements in the ATLAS experiment at CERN are presented. Measurements are based on analyses of $\sqrt{s}=13$ TeV proton-proton stable collisions collected by the ATLAS detector, with corresponding integrated luminosities of 36.1 fb$^{-1}$ or 139 fb$^{-1}$. This includes inclusive cross-section measurements in the dilepton $e\mu$ and the lepton+jets channels, which achieved significant improvements in the precision due to larger data statistics and more sophisticated techniques used. Results of $t\bar{t}$ differential cross-section measurements in three main $t\bar{t}$ system decay channels: dilepton, lepton+jets and all-hadronic resolved, are also presented. The measurement in the all-hadronic resolved channel was performed for the first time in the ATLAS experiment. All differential measurements provide double-differential spectra which allow to determine correlations between variables and which allow stringent tests of the Standard Model.