Data center capacity: distinguish booked and powered MW
Data-center capacity moves through several distinct stages: land can support a plan, a building can be constructed, electrical infrastructure can be energized, space can be leased, and customer equipment can begin operating. A megawatt at one stage cannot be added to a megawatt at another without checking overlap and definitions.
Identify the power unit and commercial stage
Digital Realty’s first-quarter 2025 materials distinguish buildable IT capacity, capacity under construction and in-place IT capacity, while describing signed leases not yet commenced. These issuer definitions illustrate separate physical and commercial stages. They do not establish that every signed megawatt is already powered or generating rent.
Clarify whether a published figure refers to utility supply, total facility load or usable IT load. Cooling and electrical overhead consume some facility power. Redundant supply paths may protect the same load rather than double the sellable capacity. Neither a utility connection request nor a power reservation alone proves a commissioned, tenant-ready hall.
A hypothetical capacity intersection
Assume a fictional operator has a 100 MW buildable IT plan. Forty MW are constructed, but only 30 MW are commissioned and powered. Signed contracts cover 35 MW: 25 MW within the powered group and ten in space awaiting delivery. Actual customer equipment currently draws 18 MW.
| Hypothetical capacity state | MW | Meaning |
|---|---|---|
| Buildable IT plan | 100 | Development envelope |
| Constructed | 40 | Includes powered and unpowered space |
| Commissioned and powered | 30 | Physical readiness |
| Signed | 35 | Commercial commitment across stages |
| Signed and powered intersection | 25 | Both conditions met |
| Current customer draw | 18 | Actual use, not contracted capacity |
Signed capacity is not a subset entirely within the powered capacity in this example. Adding 35 and 30 would double-count their 25 MW intersection. The union of signed or powered capacity is 40 MW, but even that union is not a definition of current rent-paying capacity.
Connect readiness to rent commencement
Assume the 25 MW signed-and-powered group begins rent on the first day of the quarter at 120 per kW per month. For three months, base rent is 25,000 × 120 × 3 = 9 million. If another ten MW commence only on the last day, they should not receive a full quarter of modeled rent.
Customer draw of 18 MW does not automatically reduce the contracted base rent in this example; the assumed contract charges reserved capacity. Power reimbursement and usage-based service charges must be modeled separately. Actual agreements can have ramp schedules, acceptance tests, free-rent periods and different billing structures.
Inspect the critical path
A completed shell can remain unusable while waiting for transformers, substations, interconnection approval or cooling commissioning. Conversely, power can be available before the customer’s equipment arrives. Record which party controls each remaining step and what evidence establishes completion.
Review when signed capacity grows faster than powered delivery, when expected commencement moves, or when utility capacity is stated on a different basis from IT capacity. A prelease announcement supports commercial demand but does not remove infrastructure execution risk. The evidence checkpoint should be the specific missing condition, not another broad demand statement.
Keep the inference bounded
Create a site-level matrix of capacity definition, construction state, power availability, commissioning, contracted load, commencement dates and billing terms. Public documents may omit exact intersections; preserve an unknown rather than assuming all categories nest neatly.
This is an operator-capacity and rent-timing analysis, not a forecast of AI demand or electrical engineering certification. Headline MW cannot establish margins without construction cost, power procurement, operating expense and financing. Keep those economic questions separate from proof that a particular hall can serve a customer.
Keep joint-venture ownership consistent across the capacity and rent tables. A project can be reported at full physical capacity while financial exposure is presented at the operator’s share. Multiplying full-site MW by rent and then comparing with proportionate revenue creates an artificial gap. Label gross project capacity and economic share separately, and apply ownership only at the intended aggregation step. Ownership changes can alter the reported portfolio without changing the physical readiness of the underlying hall.
FAQ
Is current customer power draw the same as leased capacity?
No. A customer may reserve capacity ahead of use. Check the contract’s billing basis and ramp terms before equating the figures.
Can two redundant feeds be added as saleable IT capacity?
Not automatically. They may support the same protected load. Use the operator’s capacity definition and the actual engineering boundary.