There are
1,844 mi
from St Charles, MO to Carlsbad, CA
That's the driving distance. It would take 1 day 8 hours to go from St Charles, Missouri to Carlsbad, California.
The flight distance (direct flight from St Charles, MO to Carlsbad, CA) is 1,544.20 mi.
1,844 mi = 2,967.32 kms