Bose-Einstein correlations of charged hadrons provide a tool to investigate the space-time structure of the hadron emitting source. In CMS we measure charged hadrons over a broad multiplicity range, from a few particles up to about 250 reconstructed charged hadrons in proton-proton collisions 13 TeV. Different analysis techniques were used to investigate the dependence on simulations when removing the non-Bose-Einstein background from the correlation functions. The measured correlation radii were studied as functions of particle multiplicity and average pair transverse momentum. The results were compared to theoretical predictions, pointing out interesting similarities and differences in hadron production in heavy ion collisions as well.