For Exchange users, three methods are available to migrate mailboxes from Exchange to Office 365.

Express migration: Express migration is suitable when the number of mailboxes is less than 2000. Migration can be started from Exchange admin Center (EAC). However, due to the prolonged time it takes to migrate 2000 mailboxes, try to migrate only 150 mailboxes or less.

Express migration can be used for migration from Exchange 2003, 2007, 2010, and 2013 versions.
Staged migration: Use Staged migration when the number of mailboxes is more than 2000. Staged migration can be performed if you are migrating from Exchange 2003 or 2007 versions.

Hybrid migration: Hybrid migration maintains both on-premises and online mailboxes, and gradually migrates data to Office 365. Always use hybrid migration if you want to migrate Exchange 2010 mailboxes (150 to 2000 in member) to Office 365 in small batches. And this is the best option to migrate Exchange 2013 to Office 365.

To know more about Migrate Exchange 2013 to Exchange Online, visit O365CloudExperts.