Tool
Migration time estimator
Enter your mailbox count, average mailbox size and shared file volume to see the raw transfer time, the discovery and permission work either side of it, and the realistic elapsed duration. Transfer speed is almost never the binding constraint below 500 seats.
| Mail data in scope | 600 GB |
|---|---|
| Drive data in scope | 2,048 GB |
| Raw transfer time | 757 hours of sync |
| Discovery and mapping | 2 working days |
| Permission remediation | 3 working days |
| Realistic elapsed duration | 15 weeks, one weekend cutover |
| Delta syncs after cutover | 2 (day 7 and day 14) |
Estimates use throughput measured on our own projects. Discovery, not transfer, is the usual constraint under 500 seats.
The elapsed figure assumes a single weekend cutover with mail delivery continuing throughout: inbound mail queues at the sending relay while MX records propagate, then delivers to the new tenant. Two delta syncs after cutover catch anything left in the source platform while users were still switching clients.
IMAP and cPanel sources run roughly three times slower per gigabyte than Microsoft 365, because there is no bulk export API and each folder is walked message by message. If your estimate looks long, the source platform is usually why.
What this doesn't cover
- Estimates assume reasonable source-side bandwidth and no throttling by the losing provider.
- Legal hold, eDiscovery continuity and archive re-indexing are separate workstreams.
- Line-of-business applications authenticating against the old directory are not included.
Questions we get asked
- How long does a Google Workspace migration take?
- A 50-mailbox migration from Microsoft 365 takes three to four weeks elapsed: five days of discovery and mapping, a weekend cutover, then delta syncs at day 7 and day 14.
- What slows a migration down most?
- Permission mapping on shared file data, not mail transfer. Every nested share and orphaned folder owner has to be resolved before cutover or users lose access on Monday morning.
Related pages
Want this estimate against your real tenant?
We run discovery on your actual mailbox sizes, shared drives and permission sprawl, then quote a fixed price and a dated cutover window.