We present a comparative experimental and theoretical study on the determination of capped core diameter in ZnSe/ZnS, CdSe/Cd(Zn)S type-I and ZnSe/CdS type-II core/shell nanocrystals. The lattice mismatch strain at the interface between core and shell semiconductors is calculated from continuum elastic theory and applied in effective mass approximation to determine the corresponding capped core diameter. Calculated results are compared with bare cores (CdSe and ZnSe) diameter obtaind from the transmission electron microscopy images. It is shown that the core is squeezed in ZnSe/ZnS and CdSe/Cd(Zn)S after compressive strained shell and stretched in ZnSe/CdS after tensile strained shell deposition. (C) 2016 The Authors. Published by Elsevier Ltd.