Migrating from Google Workspace to Microsoft 365: A Practical Guide for CTOs

Google Workspace to Microsoft 365 migrations fail for one reason: underestimating what you're actually moving. It's not just email. It's years of shared Drives, calendar history, contacts, Meet recordings, third-party integrations, and a workforce that has built their daily workflow around Google's tools. This guide covers how to do it right — on time, with no data loss, and without drowning your helpdesk.

We've run this migration for companies ranging from 80-seat professional services firms to 600-user manufacturing operations. The technical mechanics are well-documented. What this guide focuses on is the decision points, sequencing, and failure modes that don't show up in Microsoft's official documentation.

Why Companies Switch from Google Workspace to Microsoft 365

The trigger is almost always one of three things: a Microsoft-centric enterprise acquisition, an IT standardization push driven by security and compliance requirements, or an organization-wide move to the Microsoft ecosystem for better integration with Teams, SharePoint, Azure AD, and the Power Platform.

Cost is rarely the primary driver — at comparable tiers, the platforms are priced similarly. What tips the decision is usually the application depth. Microsoft 365 Business Premium includes Intune, Defender for Business, Azure AD P1, and the full Office desktop suite. For organizations that need endpoint management, advanced threat protection, and conditional access, the math shifts strongly in Microsoft's favor.

What You're Actually Moving

Before touching a migration tool, you need an honest inventory of every data category in scope. Teams consistently underestimate this — and it's where timelines blow up.

• Gmail → Exchange Online. Mailbox data including messages, labels (which map to folders), and attachments. The easy part — tools handle this well.
• Google Drive → OneDrive / SharePoint. Personal Drive maps to OneDrive; Team Drives (Shared Drives) map to SharePoint document libraries. This is the high-risk category. Volume is often 10–20x what teams expect, and permission structures rarely translate cleanly.
• Google Calendar → Exchange Calendar. Recurring events, shared calendars, and room resources all require mapping. External calendar shares (with vendors, clients) need to be rebuilt.
• Google Contacts → Exchange Contacts. Often overlooked until post-cutover, when users discover their contact lists are empty.
• Google Meet / Chat. No migration path. Users move to Microsoft Teams. Recorded meetings stored in Drive need to be either migrated or archived.
• Third-party integrations. Every app connected to Google Workspace via OAuth needs to be audited — CRM connectors, Slack, project management tools, e-signature platforms. Many will need to be re-authorized or reconfigured for M365.

Migration Tools: What Actually Works

Microsoft provides a free tool — the Google Workspace Migration for Microsoft Exchange (GWMME) — that handles Gmail and Calendar reasonably well. For Drive, you'll need something more capable.

Microsoft's Free Tools

GWMME is adequate for small migrations (under 100 mailboxes) with straightforward Gmail and Calendar data. It migrates email and calendar in batch, but has no support for Drive data, shared calendars, or contacts at scale. Expect some manual cleanup regardless.

BitTitan MigrationWiz

The industry standard for mid-market and enterprise migrations. Handles Gmail, Calendar, Contacts, Drive, and Shared Drives. Supports pre-staging (migrate data before cutover so the final delta sync is small), delta passes, and per-mailbox scheduling. Licensing is per-mailbox per migration type. For a 200-user migration covering mail and Drive, budget $15–25 per user depending on volume.

ShareGate

Best option specifically for Google Drive → SharePoint migrations. Handles complex permission mapping, provides a pre-migration report showing permission translation issues before you commit, and preserves metadata better than most alternatives. If your Drive → SharePoint migration is the high-risk leg, ShareGate is worth the licensing cost.

The Migration Sequence That Minimizes Disruption

Order matters. Running these phases out of sequence is the most common cause of avoidable downtime and data loss.

1. Provision Microsoft 365 tenants and licenses. Set up the M365 tenant, create user accounts (or sync from Active Directory via Azure AD Connect), assign licenses, and configure security baselines before migrating a single byte of data. This typically takes 1–2 weeks for a 100–500 user organization.
2. Run a Drive inventory and permission audit. Before migrating any Drive data, export a full inventory of your Shared Drives including folder structure, file count, total size, and external sharing permissions. Broken permissions discovered post-migration are extremely painful to remediate at scale.
3. Pre-stage mailbox data. Begin migrating historical email (anything older than 30 days) to Exchange Online before the DNS cutover. This is the longest-running step — plan for 1–3 weeks depending on mailbox size and volume. Users stay on Gmail during this phase.
4. Migrate Google Drive to OneDrive / SharePoint in parallel. Run the Drive migration concurrently with the mail pre-stage. Prioritize active Shared Drives over personal Drive data. Communicate clearly that files will still be in Google Drive during this phase — don't delete from Drive until migration is confirmed complete.
5. DNS cutover weekend. On the cutover day: update MX records to point to Exchange Online, run a final delta sync of email, migrate contacts and calendars, redirect any email aliases or distribution lists, and disable new mail routing to Google. Allow 48–72 hours of parallel mail flow if budget permits.
6. Post-migration cleanup. Verify all data, address permission issues surfaced by users, reconfigure third-party integrations, and disable Google Workspace licenses. Leave Google accounts in read-only mode for 30 days before deprovisioning.

The 4 Mistakes That Derail Migrations

These are the failure patterns we see most frequently — and every one of them is avoidable with proper planning at Ez IT Expert.

• Skipping the Drive permission audit. Google's sharing model (Anyone with link, specific people, domain-wide) does not map cleanly to SharePoint's permission model. If you don't audit and remediate permissions before migration, you'll either migrate broken permissions or spend weeks cleaning up access issues post-launch.
• Cutting over email before OneDrive is ready. Users switch to Outlook, expect their files to be in OneDrive, find they're still in Google Drive, and immediately lose confidence in the project. Sequence the communications so OneDrive is confirmed ready before you announce the mail cutover.
• No end-user training before cutover. Outlook behaves differently from Gmail. Teams is not Google Meet. SharePoint navigation is not Google Drive. Without at minimum 60-minute hands-on training sessions for each user group, helpdesk tickets spike 3–5x in the two weeks after cutover.
• Deprovisioning Google Workspace too fast. Users will discover data that didn't migrate for weeks post-cutover. Keep Google accounts in read-only (no new mail, no edits) for at least 30 days. The cost of one extra month of Google licenses is far less than a data recovery incident.

Licensing: What to Buy and What to Avoid

Most companies migrating from Google Workspace land on one of two Microsoft 365 tiers. Choosing wrong costs real money.

Microsoft 365 Business Standard ($12.50/user/month)

Full Office desktop apps, Exchange Online, SharePoint, Teams, OneDrive (1TB). Right for: organizations that primarily need email, file storage, and Office productivity. No advanced security features.

Microsoft 365 Business Premium ($22/user/month)

Everything in Business Standard plus Microsoft Intune (endpoint management), Azure AD P1 (conditional access, MFA policies), Defender for Business (EDR), and Azure Information Protection P1. If you're handling sensitive data, are subject to compliance requirements, or need centralized device management — this tier pays for itself. Don't try to bolt these capabilities on afterward; the architecture decisions you make at migration time affect how cleanly these features integrate.

One nuance: if you have 300+ users, evaluate Microsoft 365 E3 ($36/user/month), which includes Windows 11 Enterprise licensing — a meaningful saving if you're managing a fleet of company-owned Windows devices.

Realistic Timeline and Cost

For a 100–500 user organization with a reasonably clean Google Workspace environment:

• Planning & provisioning: 2–3 weeks. Tenant setup, user provisioning, security baseline configuration, Drive audit.
• Data migration (pre-stage): 3–4 weeks. Mail pre-stage running concurrently with Drive migration.
• Cutover weekend: 1 weekend. DNS changes, final delta sync, calendar and contacts migration.
• Stabilization: 2–3 weeks post-cutover for helpdesk support, permission cleanup, and integration reconfiguration.

Total elapsed time: 8–12 weeks from kickoff to decommission of Google Workspace. Migration tooling cost (MigrationWiz or equivalent): $15–30 per user. Professional services for a managed migration: varies by complexity, but plan for 40–80 hours of engineering time for a 200-user organization.

The Bottom Line

A Google Workspace to Microsoft 365 migration is a manageable project when the sequencing is right, the Drive data is audited before migration, and users are trained before they're cut over. The organizations that struggle are the ones that treat it as a simple "point the tools, flip the DNS switch" exercise — and discover three weeks post-cutover that half their Shared Drive permissions are broken and their helpdesk is overwhelmed.

Start with a proper data inventory. Sequence mail and Drive migrations in parallel with a controlled cutover. Keep Google accounts in read-only for 30 days post-migration. And choose your Microsoft 365 licensing tier based on your security posture requirements, not just the lowest sticker price.