There are
483 mi
from Missoula, MT to Seatac, WA
That's the driving distance. It would take 8 hours 50 mins to go from Missoula, Montana to Seatac, Washington.
The flight distance (direct flight from Missoula, MT to Seatac, WA) is 392.01 mi.
483 mi = 777.25 kms