There are
2,767 mi
from Gaithersburg, MD to Brentwood, CA
That's the driving distance. It would take 2 days to go from Gaithersburg, Maryland to Brentwood, California.
The flight distance (direct flight from Gaithersburg, MD to Brentwood, CA) is 2,381.77 mi.
2,767 mi = 4,453.56 kms