What is a .f90 file?
Fortran Source File · Code and data · IBM (John Backus); ISO committee · 1957 (Fortran); 1991 (Fortran 90)
An .f90 file is Fortran source code in free-form layout, introduced with Fortran 90. Fortran is the oldest language still in serious use and remains a workhorse of scientific and numerical computing.
What is a .f90 file used for?
Fortran (Formula Translation) appeared in 1957 and still dominates weather models, physics simulations and the numerical libraries under many Python packages, because compilers make its array math extremely fast.
The extension marks the layout: .f and .for hold old fixed-column code, while .f90 and .f95 hold modern free-form code (of any standard up to the current one). All are plain text.
How to open a .f90 file
The .f90 format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list. For a step-by-step walkthrough, see how to open a .f90 file.
Windows
- VS Code (Modern Fortran)
- gfortran (to compile)
- any text editor
macOS
- VS Code (Modern Fortran)
- gfortran
- any text editor
Linux
- VS Code (Modern Fortran)
- gfortran
- any text editor
How to convert a .f90 file
You can convert a .f90 file to exe (compiled) using a conversion tool or the export menu of an app that opens it.
.f90 file signature (magic bytes)
Programs recognise a .f90 file by the bytes at the start of the file, not by its name. These are the signatures for Fortran.
| Hex signature | Offset | Note |
|---|---|---|
| (no fixed signature) | 0 | plain text; no fixed magic bytes |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .f90 file?
An .f90 file is Fortran source code in free-form layout, introduced with Fortran 90. Fortran is the oldest language still in serious use and remains a workhorse of scientific and numerical computing.
How do I run an .f90 file?
Compile it with a Fortran compiler, for example gfortran file.f90 -o program, then run the resulting executable. Intel's ifx is a common alternative compiler.
What is the difference between .f and .f90?
Layout. .f (and .for) files use the old fixed-column format from the punch-card era; .f90 and .f95 files use the free-form layout that modern Fortran allows.
Is Fortran still used?
Very much. Weather forecasting, computational physics and HPC codebases run on Fortran, and libraries like LAPACK sit underneath tools such as NumPy.
Related formats
Sources
Details on this page were checked against authoritative references: