There are
2,058 mi
from Oshkosh, WI to Costa Mesa, CA
That's the driving distance. It would take 1 day 12 hours to go from Oshkosh, Wisconsin to Costa Mesa, California.
The flight distance (direct flight from Oshkosh, WI to Costa Mesa, CA) is 1,724.12 mi.
2,058 mi = 3,311.57 kms