There are
2,796 mi
from Gaithersburg, MD to Pleasanton, CA
That's the driving distance. It would take 2 days to go from Gaithersburg, Maryland to Pleasanton, California.
The flight distance (direct flight from Gaithersburg, MD to Pleasanton, CA) is 2,396.40 mi.
2,796 mi = 4,499.78 kms