  We present a measurement of the $W$-boson mass, $M_W$, using data
corresponding to 2.2/fb of integrated luminosity collected in ppbar collisions
at $\sqrt{s}$ = 1.96 TeV with the CDF II detector at the Fermilab Tevatron. The
selected sample of 470126 $W\to e\nu$ candidates and 624708 $W\to\mu\nu$
candidates yields the measurement $M_W = 80387\pm 12$ (stat) $\pm 15$ (syst)$ =
80387 \pm 19$ MeV$/c^2$ . This is the most precise single measurement of the
$W$-boson mass to date.
