AI Infrastructure Research Firm SemiAnalysis Forecasts 50GW of New Datacenter Capacity in 2027, With Over $1 Trillion in Leases Signed

Altimeter founder Brad Gerstner appeared on the All-In Podcast, showed SemiAnalysis's data, and stated that the firm's forecast of +43GW in 2027 is too aggressive. He thought only about 25GW would actually get built, close to half of SemiAnalysis's number, based on his "hunch." SemiAnalysis's response was blunt: let's not operate on hunches.

SemiAnalysis's core argument is not a single announcement or verbal commitment, but two trackable leading indicators: quarterly self-build construction starts (measured in megawatts) and datacenter lease contract value. The logic chain is as follows: SemiAnalysis states that given the capital intensity of building multi-hundred-MW datacenters, developers typically only spend 5% to 10% of project capital without a customer. They need a pre-lease — typically a 15- to 20-year contract with a total contract value of $30 to $50 billion per GW — to fund and develop the whole project. Therefore, signed lease value leads debt raises, which in turn leads the actual buildout. Tracking leases means tracking the front end of the construction pipeline.

From H2 2023 through H1 2025, quarterly datacenter leasing remained relatively stable, largely because Microsoft paused its large-scale rental activity — SemiAnalysis claims it called this out before anyone else in December 2024. The turning point came between August and October 2025: Oracle closed on approximately 4.5GW of datacenter IT capacity across three sites. After that, Meta, AWS, Microsoft, Google, Nvidia, AMD, Anthropic, and OpenAI all entered the market for GW-scale leases, with a long tail of neocloud companies signing hundred-megawatt-scale deals. SemiAnalysis reports that just in 2026 year-to-date, it has identified over $1 trillion in lease value that was signed and closed.