How long will your migration take?
Enter what you have and how many workers you will run. The estimate uses the same per-mailbox limits and bandwidth model MigrateX plans with, and shows the first pass, the delta pass and the cutover evening separately.
- Mailboxes —
- Files —
- Sites & shared drives —
- Teams & Chat history —
- Longest single mailbox
- —
- Delta pass before cutover
- —
- Cutover evening
- —
What the estimate is made of.
No magic — the same arithmetic MigrateX uses to plan a wave, with planning figures that real tenants land within. Inside the panel the same model switches to the rates your own project has actually measured.
- Per mailbox, a ceiling you cannot buy past. Both platforms allow roughly six messages a second per mailbox — MigrateX keeps four requests in flight against Microsoft and six against Gmail, which is where their per-mailbox limits sit. The largest mailbox alone sets the floor of any estimate.
- Workers multiply, up to the number of mailboxes. Four workers move four mailboxes at once. Doubling workers roughly halves the wall-clock until you run out of mailboxes or bandwidth.
- Files depend on the route. Between vendors, files stream through MigrateX (about 25 MB/s for the whole server). Drive to Drive copies inside Google, so only the file count matters. OneDrive to OneDrive in Microsoft streams too.
- Delta passes are small. They carry only what changed since the last pass — usually a few percent — so the cutover evening is short and predictable.
- It is a range on purpose. Throttling, attachment-heavy mailboxes and the server's own link vary; real tenants finish between 85% and 140% of the model.
| Route | Messages / s per mailbox |
|---|---|
| Microsoft 365 → Microsoft 365 | 6.0 |
| Google Workspace → Google Workspace | 6.0 |
| Microsoft 365 → Google Workspace | 5.0 |
| Google Workspace → Microsoft 365 | 5.0 |
| Exchange Server → Microsoft 365 | 4.0 |
| Zoho Mail → Google Workspace | 4.0 |
| Google Workspace → Zoho Mail | 3.5 |
Assumes ≈ 14,000 messages per GB and ≈ 800 files per GB; a team's history ≈ 5,000 messages.
Questions people ask before they plan.
How long does a Microsoft 365 tenant-to-tenant migration take?
Microsoft allows about six messages a second per mailbox with several requests in flight, so a 4 GB mailbox takes about three hours on its own. For 100 people with 4 GB mailboxes and 6 GB of OneDrive each, the first pass is about three days with four workers, or a day and a half with eight — all in the background while people keep working. The delta pass before cutover takes minutes, and the cutover evening itself is one to two hours of DNS and checks.
What decides the speed?
The platforms' own limits per mailbox (about 5–6 messages a second each with requests in flight), the number of workers running in parallel, and the server's bandwidth for files streamed between vendors. The single largest mailbox sets the floor: it cannot go faster than its own quota, however many workers you add.
Does adding workers make it faster?
Yes, almost linearly, until the number of workers reaches the number of mailboxes or the server's bandwidth. Four workers move four mailboxes at once; eight move eight. Workers are free; run as many as the server can carry.
Is Google Workspace to Google Workspace slower?
No — per mailbox it matches Microsoft: MigrateX keeps several Gmail requests in flight per mailbox, close to Google's per-user quota. Drive copies inside Google without passing through MigrateX, so file size hardly matters — file count does.
Is there downtime?
No. The first pass and every delta pass run while people work in the old tenant. The only user-visible moment is the cutover evening, when MX and Autodiscover move; mail that arrives during DNS propagation is carried across by the closing pass.
Get the real number from your own tenant.
The free assessment reads every mailbox and drive size and scores readiness — then the panel estimates with your figures instead of averages.