Nebius Mantsala · Mäntsälä, Finland
Last change recorded 2026-10-04 · Last checked 2026-10-04
Latest: Second Mäntsälä site first capacity (planned 2027) · First power · 2027-12-31 (plan) · recorded 2026-10-04
Nebius tripled Mäntsälä from 25 to 75 MW (announced October 2024, completed early 2026). A second Mäntsälä data center of up to 70 MW was announced in August 2026 for 2027; Caverion is building its 70 MW substation (about €15m) for autumn 2027. A separate 310 MW AI factory is planned in Lappeenranta from 2027. · source ◐ secondary, confidence medium
Recorded readiness — 2 of 6 applicable milestones have a dated public record
Gate to first power — target 2024-10-08 (estimate) · path: Grid supply · each step must finish its lead time before the target
2 of 2 required steps have a public date. Red = recorded date past the rule-based deadline · grey "no public date" = required step without a record · green = on record in time · context steps never colour.
| Step | Must finish by | Others did it | Known date | Status | Basis | |
|---|---|---|---|---|---|---|
| Site secured (context) | 2023-07-08 (15 mo before) | 13 mo before (n=26) | 2024-10-08 | context | Expansion to 75 MW announced · ◐ | |
| Grid supply agreed | 2024-01-08 (9 mo before) | 7 mo before (n=11) | 2027-10-31 plan | plan 46 mo past the deadline | 70 MW substation for the second site (autumn 2027) · ◐ | |
| Building ready for IT | 2024-10-08 (0 mo before) | 2 mo after (n=7) | 2026-03-31 | recorded 18 mo after the deadline | 75 MW complete (early 2026) · ◐ |
This site is energized; lights only show how its recorded steps compared with the lead times.
Lead-time assumptions
- Site secured 15 months before first power — Land under control and campus announced. Rarely binding; shown for context.
- Permits in hand 0 months before first power — Final air and siting permits. Operators often energize on standard or temporary authorisations and receive the major permit later; flagged only when the permit lands more than 6 months after first power or is missing for an on-site plant.
- Grid supply agreed 9 months before first power — Interconnection or large-load agreement approved. Observed median 7 months before first power; the physical works (substation, lines) run in parallel with construction.
- Substation and lines energized 2 months before first power — Utility delivery point live; final tests before the load is taken.
- New generation online 1 months before first power — Utility plant or on-site plant generating; needed just before energization when the grid cannot carry the load alone.
- Major equipment on site 6 months before first power — Turbines, transformers, switchgear delivered; installation and commissioning take the remaining months.
- Construction started 24 months before first power — Groundbreaking of the building that gives first power. Observed 4-26 months for recent AI campuses; Meta's redesigned campuses took 35-58.
- Building ready for IT 0 months before first power — First building ready for IT. 'Complete' or 'opened' is usually reported after first power; flagged only beyond 3 months.
- Full build-out complete -12 months before first power — All announced buildings operational. Comes after first power by design; context only.
- Water supply secured 12 months before first power — Water rights, municipal agreement or desalination contract in hand. Context only; one of the feasibility items.
- Financing closed 12 months before first power — Project financing, anchor lease or committed capital announced. Context only; not applicable when the owner is a hyperscaler building on its balance sheet.
Dated steps (from the sources; later dates are plans)
Build-out timeline (Epoch AI; dated status notes with IT power; rows after today are estimates)
Recorded fact grid supply agreed, building ready for it have a recorded date later than the rule-based deadline for a 2024-10-08 first power.
Calculated requirement Energized; watch the build-out timeline for the next buildings.
Sources (Epoch AI selection): Nebius to triple capacity of Mantsala campus to 75 MW · Nebius announcing deployment of first GB300 NVL72 systems in Europe
Epoch AI, 'AI data centers', epoch.ai/data/ai-data-centers (CC BY 4.0); coordinates from GeoNames cities500 (CC BY 4.0) and hand-entered places; overrides in tools/project_overrides.csv with their own sources. Campuses outside the Epoch dataset come from tools/campuses.csv (public reporting, source per row). Data retrieved 2026-10-05. Report a correction to contact@ailoadmap.com (campus id nebius-mantsala; include the row and a source link).