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El Capitan is an exascale supercomputer at Lawrence Livermore National Laboratory in Livermore, California, built for the National Nuclear Security Administration (NNSA). It held the number one place on the TOP500 list from November 2024 through November 2025; on the June 2026 list it ranks second, behind LineShine at the National Supercomputing Centre in Shenzhen, China. Rankings below are dated because they change twice a year.
What El Capitan is
El Capitan is NNSA’s first exascale supercomputer, funded by the Advanced Simulation and Computing (ASC) program. It is an HPE Cray EX system built with HPE and AMD, using more than 46,000 AMD Instinct APUs connected by the HPE Slingshot interconnect. Lawrence Livermore National Laboratory (LLNL) reports it as more than 20 times faster than Sierra, the system it succeeds, which has been retired (LLNL, read 2026-11-07).
Where is El Capitan located, and who runs it?
El Capitan is located at Lawrence Livermore National Laboratory in Livermore, California. It is a shared NNSA resource used by the three weapons laboratories: LLNL, Los Alamos and Sandia. Its mission is supporting nuclear stockpile stewardship, meaning the safety, security and reliability of the US nuclear deterrent (LLNL, read 2026-11-07).
How fast is El Capitan? What each TOP500 number measures
“Fastest” depends on the benchmark. The table gives the values LLNL reports from the November 2025 TOP500 list, and what each benchmark is for.
| Benchmark | What it measures | El Capitan result (Nov 2025 list) |
|---|---|---|
| HPL (High-Performance Linpack) | Speed on a dense linear-algebra problem; the benchmark that sets the TOP500 order | 1.809 exaFLOPs (verified) |
| HPCG | Speed on sparse-matrix workloads, closer to many real simulation codes | 17.41 petaFLOPs, No. 1 |
| HPL-MxP | Mixed-precision performance, relevant to AI-style workloads | 16.7 exaFLOPs, No. 1 |
| Green500 | Energy efficiency (GFlops per watt) | 60.94 GFlops/W, 23rd |
On first appearing in November 2024, El Capitan scored 1.742 exaFLOPs on HPL. On the June 2026 TOP500, LineShine is first at 2,198.40 petaFLOPs and El Capitan second at 1,809.00 petaFLOPs, while El Capitan remains first on HPL-MxP (TOP500, read 2026-11-07).
What is El Capitan used for?
Its stated purpose is stockpile stewardship for the NNSA: simulation in support of the safety, security and reliability of the nuclear deterrent, shared by LLNL, Los Alamos and Sandia. This is national-security work, not a general science facility.
Can researchers use El Capitan, and can a normal person buy a supercomputer?
El Capitan is a government facility funded under a weapons-program mission, so it is not an open allocation system for general researchers. For open scientific computing in the US, see the CASRAI guides to NSF ACCESS compute allocations and the DOE Advanced Scientific Computing Research (ASCR) program. No purchase price for El Capitan appears in the LLNL or TOP500 pages, and this page does not state one. It was built with HPE and AMD as a purpose-built government installation, not a product sold off a shelf.
Strengths and limits
- Strength: top-ranked on HPCG and HPL-MxP in the November 2025 list, which matters for workloads that do not look like Linpack.
- Limit: no longer first on the headline TOP500 (HPL) ranking as of June 2026.
- Limit: energy efficiency ranked 23rd on the Green500 (Nov 2025). For context on this topic, see sustainable HPC.
- Limit: access is tied to the NNSA mission, so most researchers will not run work on it.
Alternatives for researchers
| Option | Who it serves | Where to read more |
|---|---|---|
| NSF ACCESS allocations | US researchers requesting open computing time | NSF ACCESS guide |
| DOE ASCR programs | Researchers in DOE Office of Science computing | DOE ASCR guide |
| Other ranked systems | Each system’s own operators set access rules | TOP500 June 2026 list |
FAQ
Where is the supercomputer El Capitan located?
At Lawrence Livermore National Laboratory in Livermore, California.
What is the biggest supercomputer in the US?
El Capitan is the highest-ranked US system on the June 2026 TOP500 (second worldwide, 1,809.00 petaFLOPs on HPL). Rankings are updated twice a year, so check the current list.
Can a normal person buy a supercomputer?
Machines at El Capitan’s scale are government-procured, custom installations; no price for El Capitan is published in the sources used here.
What computer does Elon Musk use?
This page covers El Capitan only and makes no claim about any individual’s computers.
Is El Capitan still the world’s fastest supercomputer?
Not on the HPL-based TOP500 ranking as of June 2026, where it is second. It remains first on HPL-MxP.
Sources
- LLNL: El Capitan retains title of world’s fastest supercomputer on latest TOP500, read 2026-11-07.
- TOP500 list, June 2026, read 2026-11-07.
