There are
1,221 mi
from Thornton, CO to Brentwood, CA
That's the driving distance. It would take 21 hours 8 mins to go from Thornton, Colorado to Brentwood, California.
The flight distance (direct flight from Thornton, CO to Brentwood, CA) is 907.79 mi.
1,221 mi = 1.61 kms