El Capitan

El Capitan, at Lawrence Livermore National Laboratory in the US, held the top spot on the November 2025 TOP500 list at about 1.8 exaflops. That is 1.8 quintillion calculations per second.

A new list comes out each June and November.

Context

The TOP500 list ranks machines by running a standard benchmark called High-Performance Linpack, which solves a huge set of linear equations and reports how many floating-point operations per second the system sustains. The result is a measured score rather than a theoretical peak, so it is usually a little lower than the figure a vendor would quote from the hardware alone.

El Capitan is built by HPE and uses AMD processors that combine CPU and GPU parts on one package. It serves the US National Nuclear Security Administration, and its main job is to support stockpile stewardship, which means simulating the ageing and safety of nuclear weapons without explosive tests.

An exaflop is a billion billion operations a second. El Capitan has held first place since its debut on the November 2024 list. Other exascale machines exist, including Frontier in the US and Europe's Jupiter, and rankings can change at each twice-yearly update. Some very large systems never submit a benchmark run, so the list shows only machines whose owners chose to report.