Mailbox and data inventory template for Microsoft 365 migrations
Mailbox, archive, OneDrive and SharePoint sizes with item counts. Free download in Excel.
Download the mailbox and data inventory template
Record mailbox, archive, OneDrive, Google Drive, SharePoint and file share sizes with item counts so you can size waves, licences and timelines.
Free to use and adapt. Document ID CM-TPL-ASS-04, version 1.0, November 2026.
What the template includes
Sheet: Mailboxes
18 columns, with dropdowns, formulas and 5 example rows:
Sheet: Drives (OneDrive-Google)
12 columns, with dropdowns and 3 example rows:
Sheet: Shares and sites
14 columns, with dropdowns and 4 example rows:
Sheet: Totals by wave
10 columns, formulas and 4 example rows:
How to use this template
- Export statistics from the source using admin reports or PowerShell (for example Get-MailboxStatistics, OneDrive usage reports, share size scans) and paste into the matching sheet.
- Enter sizes in GB and item counts as plain numbers so the totals and flags calculate.
- Check the flag columns: large mailboxes, oversized archives and high item counts need special handling or longer pre-staging.
- Assign every row a wave and a target location; blank waves are not yet planned.
- Re-export just before each wave and update the totals so throughput estimates stay accurate.
Ready to share with your steering committee
- Branded cover or instructions page with document ID and version
- QR code linking to the latest version, and a Code128 barcode for your document register
- Document control, approval block and a clear disclaimer
- Example rows written for real migration projects, which you replace with your own
Guides that use this template
Questions about this template
Is the mailbox and data inventory template free?
Yes. Download it in Excel and adapt it for your organisation. No sign-up is needed.
Can I use it in Google Sheets or Google Docs?
Yes. Upload the file to Google Drive and open it with Google Sheets or Docs. Dropdowns and most formulas carry across; check conditional formatting after converting.
Can I remove the Cloud-Migrations branding?
Yes. Replace the logo and footer with your own. Keep the disclaimer in mind: the template is general guidance and needs adapting to your project.
How do I know I have the latest version?
Scan the QR code on the cover or instructions sheet. It opens this page, which always links to the current version.