There are
945 mi
from Simi Valley, CA to Rexburg, ID
That's the driving distance. It would take 16 hours 34 mins to go from Simi Valley, California to Rexburg, Idaho.
The flight distance (direct flight from Simi Valley, CA to Rexburg, ID) is 758.69 mi.
945 mi = 1,521.58 kms