The mass of the top quark is measured in 36.3 fb^-1 of LHC proton–proton collision data collected with the CMS detector at √s=13TeV . The measurement uses a sample of top quark pair candidate events containing one isolated electron or muon and at least four jets in the final state. For each event, the mass is reconstructed from a kinematic fit of the decay products to a top quark pair hypothesis. A profile likelihood method is applied using up to four observables per event to extract the top quark mass. The top quark mass is measured to be 171.77±0.37GeV . This approach significantly improves the precision over previous measurements.