is FORTRAN still used, for what? (2026)

fortran usage (ai answer)

Where is Fortran used today, the programming language?

Fortran is still heavily used in scientific computing and high-performance applications. It's dominant in numerical weather prediction, climate modeling, computational fluid dynamics, physics simulations, and supercomputing benchmarks. Major centers like NOAA, NASA, ECMWF, and NCAR rely on it for core models because of its speed with large arrays and decades of optimized legacy code that's too expensive to rewrite.

• NOAA → The National Oceanic and Atmospheric Administration
• NASA → National Aeronautics and Space Administration
• ECMWF → European Centre for Medium-Range Weather Forecasts
• NCAR → National Center for Atmospheric Research

You’ll also find it in computational chemistry, astronomy, structural engineering, and even some financial risk modeling where raw numerical performance matters. It climbed back into the TIOBE top 10 recently thanks to its role in HPC. Modern Fortran is actively developed and pairs well with Python or C for newer projects.

Do they run on mainframes or what computers they run on?

Mostly on supercomputers and massive compute clusters. These are huge Linux-based systems with thousands of CPUs, often accelerated by GPUs. That's where weather models, climate simulations, and physics codes run.

Some legacy Fortran still runs on IBM mainframes under z/OS, but that's not where the big scientific stuff happens today. The heavy lifting is all on modern HPC hardware.