Google Workspace to Microsoft 365 Migration: The Real Timeline and Cost

Why Organizations Move from Google Workspace to Microsoft 365

The decision to migrate from Google Workspace to Microsoft 365 is typically driven by one or more enterprise requirements that Google cannot adequately address. Common drivers include:

• Enterprise security and compliance: Microsoft 365 E5 provides significantly deeper security capabilities including Microsoft Defender XDR, Purview Information Protection, insider risk management, and advanced eDiscovery. Organizations in regulated industries (healthcare, finance, government) find Microsoft's compliance tools more comprehensive.
• Desktop application requirements: Google Docs, Sheets, and Slides lack the advanced features of Word, Excel, and PowerPoint that enterprise users depend on. Complex Excel financial models, Word document automation with VBA, and PowerPoint corporate templates do not translate to Google's web-only editors.
• Microsoft ecosystem integration: Organizations using Azure, Dynamics 365, Power Platform, or Teams Rooms benefit from the deep integration between Microsoft 365 and these services. Google Workspace operates as an island within the Microsoft ecosystem.
• Cost optimization at scale: For enterprises over 1,000 users needing security and compliance features, Microsoft 365 E3/E5 often provides better value than Google Workspace Enterprise Plus with equivalent third-party security add-ons.

The Real Migration Timeline: 8-16 Weeks

Migration vendors and Microsoft marketing materials suggest migrations can be completed in days. This is misleading. A responsible enterprise migration takes 8-16 weeks to execute properly, and rushing it causes data loss, user disruption, and extended support costs.

Phase 1: Assessment and Planning (Weeks 1-3)

The assessment phase determines the entire migration scope and timeline. Shortcuts here cause cascading problems later.

• User and license inventory: Map every Google Workspace user to a Microsoft 365 license tier. Not every user needs E5. Most organizations use a mix of E3, E5, and F3 (frontline) to optimize costs.
• Data inventory: Catalog all Google Drive files (total volume, file types, sharing permissions), Gmail mailboxes (size, archive depth), Google Sites (count, complexity), Sheets with Google-specific functions, and Forms/AppSheet applications.
• Identity assessment: Document the current identity provider (Google as IdP, third-party IdP, federated SSO), multi-factor authentication configuration, and group/OU structure for mapping to Entra ID and Microsoft 365 groups.
• Integration inventory: Identify all third-party applications using Google SSO, Google Drive APIs, Gmail APIs, or Google Workspace Marketplace apps. Each integration needs a migration plan to Microsoft equivalents.
• Risk assessment: Identify high-risk users (executives, legal, finance) who need white-glove migration support and define rollback procedures for each migration phase.

Phase 2: Identity and DNS Preparation (Weeks 3-5)

Identity migration is the foundation that all data migration builds upon. Getting this wrong breaks everything else.

• Entra ID tenant configuration: Create the Microsoft 365 tenant, configure Entra ID, set up custom domains, and configure DNS records (TXT verification, autodiscover CNAME). Do NOT change MX records yet.
• User provisioning: Create Microsoft 365 user accounts matching Google Workspace identities. Use Azure AD Connect if syncing with on-premises Active Directory, or bulk provision via PowerShell/CSV import for cloud-only deployments.
• Group mapping: Map Google Groups to Microsoft 365 Groups, distribution lists, and security groups. This mapping defines SharePoint site permissions, Teams membership, and email distribution post-migration.
• SSO and MFA configuration: Configure Entra ID conditional access policies, MFA requirements, and any federated SSO with third-party identity providers. Test authentication flows before proceeding.

Phase 3: Data Migration (Weeks 5-11)

Data migration is the longest phase and requires careful orchestration across multiple workloads.

Gmail to Exchange Online

Gmail migration to Exchange Online uses IMAP migration or third-party tools (BitTitan MigrationWiz, AvePoint). Third-party tools are recommended for enterprises because they handle labels-to-folders conversion, calendar migration, and contact migration that native IMAP migration cannot. Migration throughput averages 1-2GB per mailbox per hour. For 500 users with average 10GB mailboxes, plan for 5-7 days of continuous migration.

Google Drive to OneDrive and SharePoint

This is typically the most complex workload. Key considerations include:

• Personal Drive to OneDrive: Individual user files migrate to OneDrive for Business. Google Docs, Sheets, and Slides automatically convert to Word, Excel, and PowerPoint formats. Conversion is generally reliable but Google-specific features (ARRAYFORMULA, IMPORTRANGE, Apps Script) break during conversion.
• Shared Drives to SharePoint: Google Shared Drives map to SharePoint document libraries. Permission mapping is critical as Google's link-sharing model differs from SharePoint's permission inheritance model. Every sharing link must be evaluated and mapped.
• File path length: SharePoint has a 400-character path limit. Google Drive allows longer paths. Identify and remediate files exceeding the limit before migration to prevent failures.
• Version history: Most migration tools can transfer version history, but this significantly increases migration volume and time. Decide whether to migrate full version history or only the current version based on compliance requirements.

Google Calendar to Exchange Online

Calendar migration includes personal calendars, shared calendars, conference room bookings, and recurring event series. Third-party migration tools handle most calendar objects, but complex recurring events with exceptions and conference room resource migration require manual validation.

Phase 4: Coexistence and Testing (Weeks 11-13)

During coexistence, both Google Workspace and Microsoft 365 are active simultaneously. This phase validates that all migrated data is accessible and that cross-platform communication works seamlessly.

• Mail coexistence: Configure mail routing so users on both platforms can send and receive email. Typically, MX records point to one platform with forwarding rules for the other. Dual delivery or split routing ensures no email is lost.
• Calendar federation: Configure free/busy lookup between Google Calendar and Exchange Online so users on both platforms can schedule meetings without conflicts.
• Pilot group testing: Migrate a pilot group (25-50 users from IT and early adopters) to Microsoft 365 while the rest remain on Google Workspace. The pilot group validates all workflows, identifies issues, and builds internal champions.

Phase 5: Cutover and Post-Migration (Weeks 13-16)

• MX record cutover: Switch MX records to Exchange Online during a low-traffic window. Monitor mail flow for 48 hours after cutover to catch any routing issues.
• Google Workspace deprovisioning: Do not immediately decommission Google Workspace. Maintain read-only access for 30-90 days so users can reference historical data during the transition. Then archive Google data per retention requirements.
• User training: Provide role-based training for Outlook, Teams, OneDrive, and SharePoint. Focus on workflow differences rather than feature tours. Executives, power users, and general users each need different training content.
• Hypercare support: Dedicate 2 weeks of enhanced support post-cutover. Track and resolve issues rapidly to maintain user confidence in the new platform.

The Real Cost Breakdown

Licensing Cost Comparison

When evaluating total cost of ownership, compare equivalent feature tiers between Google Workspace and Microsoft 365:

The comparison is not apples-to-apples. Microsoft 365 E5 includes security and compliance features that would require third-party add-ons with Google Workspace. When factoring in Google Workspace Enterprise Plus + Workspace security add-ons + third-party DLP/eDiscovery, Microsoft 365 E5 is often cost-competitive or cheaper for organizations with compliance requirements.

Google Sites to SharePoint Migration

Google Sites migration to SharePoint Online is one of the most labor-intensive workloads because there is no automated migration path. Each site must be rebuilt in SharePoint using modern site pages, web parts, and navigation.

EPC Group categorizes Google Sites into three tiers for migration planning: simple informational sites (2-4 hours each to rebuild), moderate sites with embedded content and navigation (1-2 days each), and complex sites with Google integrations and dynamic content (3-5 days each, may require Power Pages or custom development).

Partner with EPC Group for Your Migration

EPC Group has managed hundreds of Google Workspace to Microsoft 365 migrations across healthcare, financial services, education, and professional services organizations. As a Microsoft ecosystem specialist with 25+ years of experience, Errin O'Connor leads migration engagements that prioritize zero data loss, minimal disruption, and long-term platform optimization. Our Microsoft 365 consulting team provides end-to-end migration services including assessment, planning, execution, training, and post-migration support.