Guide
Google Workspace to Microsoft 365 migration: what it costs to get right
Updated
The mail is the easy part. The cost in a Google Workspace move sits in Drive, shared drives, calendar sharing and the habits people have built around Google's collaboration model.
What is actually in scope
- Mail. Gmail can be migrated to Exchange Online, and Microsoft documents a specific Google Workspace path alongside the generic IMAP route. If the generic IMAP route is used, Microsoft's stated limits apply: mail folders only, no contacts, calendar items or tasks.
- Calendars. Meetings, recurring series, room resources and external sharing all need explicit handling. Broken recurring meetings are the most visible failure of a rushed migration.
- Contacts. Personal contacts and any shared directory, which behave differently from mail and need their own step.
- Drive and shared drives. Volume, nested sharing and Google-native file formats. Native Docs, Sheets and Slides are converted, and conversion is never perfectly lossless for complex documents.
- Groups, aliases and delegation. Google Groups, delegated mailbox access and send-as permissions all have Microsoft equivalents, but they are configured, not copied.
Where the cost concentrates
| Workstream | Main cost driver |
|---|---|
| Mailbox migration | Mailbox count and data volume, plus the fidelity the chosen method supports |
| Calendar and contacts | Recurring series, room and resource calendars, external sharing arrangements |
| Drive and shared drives | Total volume, depth of nested sharing, and how much data is genuinely still needed |
| Native file conversion | Number and complexity of Docs, Sheets and Slides files, and how much manual checking is acceptable |
| Identity and domain cutover | Directory setup, domain verification and the sequencing of the mail flow switch |
| User change support | Headcount, and how different the new way of working is from the old one |
The decision that saves the most money
Decide what does not move. Most Google Drive estates contain years of material nobody will open again, and every gigabyte carried across costs transfer time, checking time and storage. A cleansing exercise before migration is usually cheaper than migrating everything and tidying afterwards, and it is work your own team can do while the partner builds the tenant. Ask explicitly whether data cleansing is in the partner's scope or yours, because both answers are reasonable and only one of them is in the price.
What to ask before comparing quotes
- Which migration method, and what fidelity? Get it in writing: mail, calendar, contacts, tasks, rules, delegate access, aliases, and what will not carry across.
- Is Drive in scope, and how much of it? A quote covering mail only, next to one covering mail and 4TB of Drive, is not a comparison.
- How are Google-native files handled? Converted, left in place with links, or exported. Each has a different cost and a different user experience afterwards.
- What happens to the old tenant? How long Google Workspace runs in parallel, who pays for that overlap, and when it is decommissioned.
- What post-migration support is included? The first Monday is when the real support demand arrives.
Microsoft 365 licences are bought separately and priced per user per month by Microsoft, independently of the migration fee. Check current plans and prices with Microsoft, and see licensing versus migration cost.