There are
1,241 mi
from Thornton, CO to Larkspur, CA
That's the driving distance. It would take 21 hours 22 mins to go from Thornton, Colorado to Larkspur, California.
The flight distance (direct flight from Thornton, CO to Larkspur, CA) is 952.20 mi.
1,241 mi = 1.61 kms