There's no direct conversion between Michigan and California college credits. The credit systems aren't standardized across states. A course that earns 3 credits in Michigan might be equivalent to 2, 3, 4, or even more credits in California, depending on the specific course, the institution, and how the institution defines credit hours.
You'd need to have each individual Michigan course evaluated by a California institution to determine its credit equivalency. Many California colleges have a process for transfer credit evaluation.