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Blog/2026-10-07

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Project Rainier: Amazon's Anthropic cluster

Amazon says Project Rainier reached nearly 500,000 Trainium2 chips in October 2025; Epoch AI now estimates about 1.04 million at New Carlisle, Indiana alone. Neither figure is audited, and the Mississippi campuses are not confirmed as part of it.

Project Rainier is the AWS cluster built for Anthropic, centred on a campus near New Carlisle, Indiana. Amazon says it is fully operational with nearly half a million Trainium2 chips, and Anthropic says it now uses over one million Trainium2 chips to train and serve Claude. Epoch AI, an independent research group that models data centers from satellite imagery and permits, puts New Carlisle alone at about 1.04 million Trainium2 chips and 910 MW of IT power. Those three numbers are not in conflict so much as taken at different dates and with different scopes, and none of them is an audited count. What is not known: the exact chip count, the cluster’s power draw, which sites beyond Indiana belong to Rainier, and whether the two large Mississippi campuses in our data (Canton and Ridgeland) are part of it. We keep them as separate rows for that reason: Project Rainier, AWS Madison Mega Site (Canton) and AWS Ridgeland Campus.

How Rainier came to exist

The name surfaced at AWS re:Invent in December 2024. Trade press coverage of the keynote, as reported by Techstrong, has Anthropic’s chief compute officer Tom Brown saying the project needs access to hundreds of thousands of processors, with Trainium2 used instead of GPUs. We could not retrieve the AWS keynote text itself, so the December 2024 date and the quote rest on that secondary report. Our own row carries no announcement date for the same reason.

The physical build started earlier. Epoch’s timeline for New Carlisle has land clearing beginning in February 2024 on the northern section and June 2024 on the southern section, and Amazon’s $11 billion Indiana investment was announced in 2024 and described as the largest capital investment in the state’s history. That figure is a campus total, not a cluster-only cost, which is how our capex row for Rainier records it.

Amazon’s account is that the cluster was “fully operational, less than one year after it was first announced”, with Anthropic already running workloads on it. Our row dates first operation to October 2025, taken from the 29 October 2025 update of that page. Epoch’s reading is more gradual: buildings 1 to 7 operational by June 2025, 8 to 11 by December 2025, 12 to 16 by March 2026. Under that reading Amazon’s October 2025 statement describes a cluster still being filled, not a finished one.

Who owns it and who pays

Amazon owns the buildings and the chips. Epoch lists Amazon as owner and Anthropic as user for New Carlisle, and a New York Times report syndicated by The Nightly says the campus was built specifically for Anthropic and that Amazon had invested $8 billion in the start-up. That report also describes a 1,200-acre farmland site with seven buildings finished and about 30 planned, around 4,000 workers on site each week, and tax breaks it values at roughly $4 billion for a 50-year sales tax exemption plus a further roughly $4 billion over 35 years. Those are the newspaper’s estimates, not Amazon’s.

Indiana’s incentive package, per Construction Dive, included sales tax exemptions, up to $55 million in Hoosier Business Investment tax credits and up to $7 million for State Road 2 improvements.

The commercial terms sit in the April 2026 expansion. SiliconANGLE’s report and Anthropic’s own post agree on the shape: Anthropic commits more than $100 billion over ten years to AWS technologies, with up to 5 GW of new capacity, and Amazon invests $5 billion with up to $20 billion more later, on top of the earlier $8 billion. Anthropic’s post calls Rainier “one of the largest compute clusters in the world” but does not give a site list or a chip count for it.

The hardware

Rainier is built from Trainium2, Amazon’s own training chip. AWS’s Trn2 page lists 16 chips per instance with 20.8 petaflops of FP8 compute, 1.5 TB of HBM and 46 TB/s of memory bandwidth. A Trn2 UltraServer links four instances over NeuronLink into 64 chips, 83.2 petaflops, 6 TB of HBM and 185 TB/s. Amazon’s Rainier page matches the layout: 64 chips per UltraServer, NeuronLink inside it, and Elastic Fabric Adapter between UltraServers across buildings. By our arithmetic, “nearly half a million” chips is about 7,800 UltraServers, though Amazon gives no server count.

Amazon makes two relative claims about scale: the infrastructure is 70 percent larger than any other AI platform in AWS history, and it offers more than five times the compute Anthropic used for its previous models. Both are comparisons to unnamed baselines and cannot be checked.

Trainium3 is the next step. AWS’s Trainium page lists up to 2x the compute of Trainium2, 144 GB of HBM3e per chip and UltraServers of up to 144 chips. Anthropic’s April 2026 post says nearly 1 GW of Trainium2 and Trainium3 capacity is due online by the end of 2026, which suggests newer capacity will be a mixed Trainium2 and Trainium3 fleet.

Power, cooling and the Indiana footprint

Amazon has never stated a power figure for Rainier. Our dataset holds Epoch’s estimate: 910 MW of IT power and 1,092 MW of facility power as of June 2026, flagged as modelled, not operator-stated. Epoch projects 1,925 MW by the first quarter of 2028 as buildings 19 to 32 arrive. The New York Times report gives a different, higher figure, 2.2 GW of electricity consumption, without saying whether that is current load, contracted supply or the full build-out. We would not read it as a measurement.

A separate Indiana number is easy to misattribute. Amazon’s $15 billion Northern Indiana announcement adds 2.4 GW of capacity through a power arrangement with NIPSCO, and says it brings the same infrastructure that powers Project Rainier. The page presents this as a further project in addition to the $11 billion New Carlisle campus, so we do not attribute the 2.4 GW to Rainier.

On cooling, Amazon states that the Indiana site uses no water for cooling from October to March and only a few hours a day from April to September, with a water usage effectiveness of 0.15 litres per kWh against an industry figure it gives as 0.375. Epoch records direct air-based cooling, while the Times describes both air and water systems. These are compatible: air most of the year, water at peak.

Mississippi: Canton and Ridgeland

Amazon has two large campuses in Madison County, Mississippi. Mississippi’s economic development agency announced a further $11 billion for Madison County on 9 April 2026, on top of the $10 billion announced in 2024, framed around generative and agentic AI and with Entergy Mississippi named as the power supplier. The Mississippi Free Press adds that Amazon must cover substation and transmission upgrades, that Ridgeland would use groundwater about 30 days a year, and that the plans include more than 800 generators across existing Madison County campuses.

Neither page gives chip counts or megawatts. Those come from Epoch alone:

CampusTrainium2 (Epoch)IT power (Epoch)Modelled costEpoch’s projection
Cantonabout 326,600284 MW$10.8 bn783,700 chips, 683 MW by Q1 2028
Ridgelandabout 261,200228 MW$8.6 bn502,400 Trainium3, 840 MW by Q3 2028

Epoch dates Canton buildings 1 to 5 as operational by June 2025 and Ridgeland buildings 1 to 4 by May 2026. It lists Anthropic as a speculative user for both and says Ridgeland is likely part of the Anthropic and Amazon collaboration. That is Epoch’s inference, and Amazon has not confirmed it. Adding Epoch’s three figures gives about 1.63 million Trainium2 chips, which is above Anthropic’s “over one million” in use. That gap is a reason to be careful: either some Mississippi capacity is not yet serving Claude, or Epoch’s counts run high.

What the numbers do and do not show

The counts line up better than they first appear. Amazon’s nearly 500,000 is an October 2025 figure. Epoch’s 1,044,980 for New Carlisle is dated 23 March 2026, after its buildings 8 to 16 came online, so the two can both be right if the cluster roughly doubled in five months. Amazon also said it expected Claude to be running on over one million Trainium2 chips by the end of 2025, which Anthropic’s April 2026 statement is consistent with, although that target covers training and inference and is not stated to be Indiana only. Our dataset records this as a design target, separate from the operator-stated 500,000.

One caution about Epoch’s own figures: its chip counts and power estimates are not independent of each other. Dividing its IT power by its chip count gives about 870 W per Trainium2 chip at New Carlisle (910 MW over about 1.045 million), about 870 W at Canton (284 MW over 326,600) and about 873 W at Ridgeland (228 MW over 261,200). That near-identical ratio is what a model that scales one from the other would produce, so the three campuses should be read as one set of assumptions applied three times, not as three separate confirmations. Epoch says its power estimates come from satellite imagery, permits and cooling equipment, and its chip estimates from the same inputs plus chip availability. If the per-chip allowance is wrong, every count moves together.

What the numbers do not show is utilisation, performance or cost. Epoch’s capex for New Carlisle is a modelled $34.5 billion including compute, against Amazon’s $11 billion for the campus. The first is chips plus buildings, the second is Amazon’s announced construction investment, so the two are not comparable. An FP8 figure from the Trn2 page, scaled by chip count, would give a peak number, but peak figures say little about what a cluster of this size delivers on a real training run, and neither Amazon nor Anthropic has published one.

For the watch list: whether Amazon or Anthropic names the Rainier site list; how quickly Trainium3 appears in Indiana or Mississippi; the New Carlisle buildings 17 to 32 that Epoch projects through March 2028; and any state filing that states a load for the Mississippi campuses.

What we could not confirm

  • An exact Trainium2 count for Rainier. Amazon gives “nearly half a million” and a target above one million; Epoch gives a different, later number.
  • Any operator statement of Rainier’s power draw. The 910 MW figure is Epoch’s model, and the 2.2 GW figure comes from a newspaper without a stated scope.
  • Whether Canton and Ridgeland are part of Rainier. Epoch calls the link speculative or likely, and neither Amazon nor Anthropic says so in the pages we read.
  • The December 2024 announcement details, because we could not open AWS’s own keynote text and rely on a trade report of it.
  • The final building count at New Carlisle. Epoch counts up to 32 buildings by 2028 from permits and the Times says about 30 are planned; Amazon has not published a number.
  • Anthropic’s share of capacity. Epoch lists Anthropic as user of New Carlisle, but Anthropic’s post does not break out sites.

Sources

deep-diveai-clustersacceleratorspower-and-cooling