It is very difficult to estimate the duration of a migration. Because Migrator relies entirely on Google’s APIs to move data, there can be a lot of variability in how long a user’s migration will take.
We can provide an approximate rate of data transfer for the five Google services that can be migrated. For all services other than Gmail, we generally see speeds of 500MB to 1GB per user per hour. For Gmail, Migrator can move around 12,500 emails per user per hour.