NBIS Stock Mäntsälä Data Center

Mäntsälä is where Nebius's operating history and its next phase of expansion now sit beside one another. The first Finnish facility completed an expansion to as much as 75 MW earlier in 2026. A second Mäntsälä development has been announced separately, with up to 70 MW and capacity expected from 2027. Those are two projects with different delivery stages, not interchangeable descriptions of the same building.

That distinction is the starting point for this guide. The established facility provides an operating base; the second project extends the development opportunity. Neither facility envelope is a measurement of GPUs actively working for customers.

The Nebius infrastructure overview connects both projects with the complete site directory. The Nebius Data Center Tracker provides the location-level view and source dates.

The first facility has expanded

Nebius's March 31 Finnish announcement reported that the expansion of its first Mäntsälä data center to up to 75 MW had been completed. It also identified an operational NVIDIA GB300 NVL72 deployment there. Those are specific company statements about the established site. Nebius's Finnish expansion announcement.

Completion of the facility expansion does not establish that every megawatt is occupied by customer IT equipment. A campus needs supporting electrical and cooling systems, and equipment deployment can continue within an expanded facility. Readers should retain the distinction between the building's capacity and the actual computing service available at a particular time.

The second Mäntsälä project is additional development

Nebius subsequently announced another facility in Mäntsälä, describing a separate project of up to 70 MW with capacity expected from 2027. That project belongs alongside the original facility in the directory. Its announced schedule remains a plan until the relevant construction, commissioning and customer milestones occur. Nebius's second Mäntsälä announcement.

It is also separate from Lappeenranta. Finland is a national operating market, not a single campus. Combining all Finnish announcements under the original Mäntsälä address would obscure both the scale of the expansion and the work still required at the newer locations.

Heat reuse connects the facility to its surroundings

Mäntsälä's cooling system has an additional role beyond protecting computers: recovered heat can serve the local district-heating network. Nebius's March announcement reported approximately 4,000 tonnes of avoided heat-production emissions during 2025 and lower heating costs for connected households. These are company-reported outcomes for that period, not an assumption that every later deployment will produce the same result.

The physical connection matters. Heat reuse requires a recipient, suitable temperature conditions and infrastructure linking the data center to the heat network. A server produces heat whenever it operates, but useful heat delivery depends on more than the existence of that heat. The arrangement is therefore a site characteristic to understand rather than a generic credit to apply to every Nebius campus.

Read the service network separately

Nebius lists Finland as public cloud region eu-north1. That tells customers where a service region is located; it does not allocate a region's resources between every existing and future Finnish building. Nebius region documentation.

For infrastructure analysis, the next useful evidence is the deployment and acceptance status within Mäntsälä 1 and the achieved development stages of Mäntsälä 2. The first has an expanded operating foundation. The second has a disclosed plan. Keeping that distinction visible makes the Finnish footprint more useful than a single combined power headline.

The Nebius company page contains the wider research and separately dated model reports. This factual study was reviewed through September 17, 2026.