cloudM Platform has a tool that estimates migration times and indicates how much is left when finished, using total data volume and current throughput (the speed at which data is processed). This function requires that the migration is already in progress and consists of a rough estimate of the remaining time. Accurately estimating the duration of the migration before it begins is really difficult, due to the large number of variables involved and the various limiting factors such as bandwidth, machine specifications, and platform throttling. Because of these factors, ideally, the following data should be collected to estimate the migration duration, both in total and per user: - Total number of users / units / sites to be migrated - Data volume - Total number of e-mail messages and files - Data distribution (number/volume of items per user) - Number of file permissions - Number of file folders Contact our team for assistance. Migration architecture: information about the source platform can help in designing the migration architecture, e.g., the number of CloudM Migrate Self-Hosted secondary instances needed for the migration. Each instance runs 20 concurrent threads by default, and since the limiting factor in almost all migrations are cloud platform throttling and API quotas, the number of threads is critical in determining the expected duration.   Calculation: Since platform limits during migrations are generally found in elements per second/user, it also means that the number of elements is as important, if not more important, than the volume of data. Our internal testing (using real-world migration results and best practices) determined an average of 40,000 mail items per instance / 2,000 items per thread per hour. As a rule of thumb, a migration lasts as long as its largest user, so this can be used to calculate an estimated total duration, provided there are enough threads available to complete the remaining users in this time frame. Migration batches can be used to ensure that larger users use the available thread time most effectively.   File migrations: if migrating to Google Drive or Sharepoint / OneDrive, there are additional factors that should be considered. Specifically: the number of permissions, as this increases the number of API calls required and the likelihood of throttling; and the number of folders, as these need to be retrieved during each execution of the migration (whereas files are only processed if they have changed since the first execution ).