We have measured the W-boson mass MW using data
corresponding to 2.2 fb-1 of integrated luminosity collected in
pp̅ collisions at √s=1.96 TeV with the CDF II detector at the
Fermilab Tevatron collider. Samples consisting of 470 126 W→eν
candidates and 624 708 W→μν candidates yield the measurement
MW=80 387±12stat.±15syst.=80 387±19 MeV/c2. This is the
most precise measurement of the W-boson mass to date and significantly
exceeds the precision of all previous measurements combined.