The W boson mass is a crucial parameter in the standard model of particle physics, providing constraints on the mass of the Higgs boson as well as on new physics models via quantum loop corrections. Bo Jayatilaka describes the measurement of the W boson mass using data corresponding to 2.2/fb of integrated luminosity collected with the CDF II detector. The measurement, performed using electron and muon decays of W bosons, yields a mass of 80387±19 MeV. This represents the single most precise measurement of the W boson mass ever performed, significantly surpassing the precision of all prior measurements combined. An updated world average of the W boson mass, including all recent Tevatron measurements, as well as the resulting standard model implications, is presented.