Three doubling times are in circulation
On 1 August, Epoch AI updated the database it keeps of the world's AI data centres. It now tracks 12.8 million H100 equivalents across 75 sites, assembled from high resolution satellite imagery, construction permits and company statements, and the organisation estimates that this represents about 27 percent of the AI compute delivered worldwide. Two days earlier the New York Times had built a long feature on Epoch's work, describing an incoming deluge of computing power: roughly 20 million AI chips in data centres today, doubling about every nine months, roughly 200 million by the end of 2028.
The buildout is real and that reporting is careful. The difficulty is the constant. Epoch publishes at least three different doubling times for AI compute, they measure different objects, and the one that has entered general circulation is not the one that describes a worldwide count of chips.
The nine month figure is about 57 machines
The nine months comes from Trends in AI Supercomputers, a paper by Konstantin Pilz, James Sanders, Robi Rahman and Lennart Heim submitted in April 2025. It builds a dataset of 500 AI supercomputers from 2019 to 2025 and finds that computational performance doubled every nine months, while hardware acquisition cost and power needs both doubled every year. Epoch's shorter data insight narrows the sample to 57 leading systems, those ranking in the top ten most powerful when first operational, and states plainly that these clusters account for roughly 10 to 20 percent by performance of all AI chips produced up to January 2025. The nine months decomposes into 1.6 times more chips per year multiplied by 1.6 times more performance per chip.
So the figure describes the peak throughput of the largest machines, measured to a cut off in early 2025 and published before the current build cycle began. Epoch's capacity series, published on 9 January 2026, answers a different question and gives a different number: global computing capacity growing 3.3 times per year since 2022, with a 90 percent interval of 2.7 to 4.1, which is a doubling every seven months. That series carries its own caveat in plain language. Its data tracks chip sales, not deployments, and it is expressed in H100 equivalents rather than raw chip counts. Neither series counts chips in service. Epoch does not publish one that does.
The same projection, run three ways
From August 2026 to the end of 2028 is about 29 months. Take the reported 20 million as the starting count and apply each published constant in turn. At a nine month doubling the multiple is 9.3, which lands at roughly 186 million and is where the reported figure of about 200 million, or ten times current levels, comes from. At the seven month rate the multiple is 17.7, or roughly 354 million. And there is a third path: if total capacity grows 3.3 times a year while each new chip is about 1.6 times faster than the one before, which is Epoch's own decomposition, then the number of chips grows around 2.1 times a year, a doubling of roughly twelve months, which gives a multiple of 5.3 and about 107 million.
That arithmetic is ours, applied to Epoch's published constants; it is not Epoch's projection and the institution has not endorsed it. But the spread is the finding. Three rates from one research group, applied to one starting number over one window, produce answers that differ by more than three to one. None of the rates is wrong. They answer different questions, and the difference between them is invisible by the time a number reaches a slide. Any capacity assumption carried into a three year budget quietly inherits whichever constant the source happened to pick up.
Europe counts chips, Epoch counts equivalents
There is a European illustration of this unit problem sitting in the open right now. On 30 July the EuroHPC Joint Undertaking opened its tender for AI gigafactories, up to 10 billion euros of public money against a target of at least 20 billion more from private investors. Four smaller facilities must each hold at least 75,000 AI chips and can draw up to 500 million euros; three larger ones must each hold at least 100,000 chips and can draw up to 1 billion. Bids close on 12 November and awards are expected in early 2027.
Now set those thresholds beside Epoch's measurement of the current record holder, a single facility at about 1.1 million H100 equivalents. The two figures are not comparable, and that is exactly the point. The European tender is specified in chips. Epoch's benchmark is denominated in H100 equivalents, a normalised unit in which one modern accelerator counts for several. A programme written in chips and a benchmark written in equivalents will diverge further every year that per chip performance improves, which is the same effect that separates the seven month curve from the nine month one. When you are sizing capacity, the unit is not a footnote.
The curve that reaches your invoice
Epoch also publishes the number that actually decides your bill, and it attracts almost no attention. Computing performance per dollar is improving at 1.37 times a year, a doubling every 2.2 years, which is about 26 months. Set that against capacity doubling every seven. Supply is compounding somewhere between three and four times faster than price performance. Abundance upstream does not arrive downstream as cheapness. It arrives as a great deal more capacity at a unit price that is falling slowly, and the gap between those two curves is where a compute budget goes wrong.
The buyers' own disclosures describe the same gap from the other side. Amazon has guided to about 200 billion dollars of capital expenditure this year, Microsoft to roughly 190 billion, Alphabet to between 175 and 185 billion, and Meta to as much as 145 billion, citing higher component costs among the reasons. Microsoft told investors that roughly 25 billion dollars of its 190 is component price inflation rather than additional hardware. When Alphabet raised its 2026 capital budget alongside second quarter results, its shares fell 7 percent. Epoch puts five hyperscalers at 71 percent of global AI compute. The deluge is being funded by a small number of buyers who are themselves watching unit costs rise, and it lands inside their own fleets first.
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