The boson mass is measured using proton-proton collision data at
TeV corresponding to an integrated luminosity of 1.7 fb
recorded during 2016 by the LHCb experiment. With a simultaneous fit of the
muon distribution of a sample of decays and the
distribution of a sample of decays the boson mass is
determined to be \begin{equation*} m_{W} = 80354 \pm 23_{\rm stat} \pm 10_{\rm
exp} \pm 17_{\rm theory} \pm 9_{\rm PDF}~\mathrm{MeV}, \end{equation*} where
uncertainties correspond to contributions from statistical, experimental
systematic, theoretical and parton distribution function sources. This is an
average of results based on three recent global parton distribution function
sets. The measurement agrees well with the prediction of the global electroweak
fit and with previous measurements.