Chmod Calculator
Works out chmod permission values and commands by ticking boxes, so you do not have to remember what rwx maps to.
Compute your chmod permissions and commands with this online chmod calculator.
Steps and notes
What is Chmod Calculator — Unix File Permissions (755, 644, 777)?
chmod controls who can read, write and execute a file on Linux and macOS. Permissions are grouped for the owner, the group and everyone else, and each group is a sum of read (4), write (2) and execute (1) — which is why 755 reads as rwxr-xr-x.
- Tick read/write/execute for owner, group and others
- The numeric form (e.g. 755) and symbolic form update above
- Copy the generated chmod command
- Be careful granting execute permission, and especially careful with 777
Frequently asked questions
- What does 755 actually mean?
- The owner gets read, write and execute (7 = 4+2+1); the group and others get read and execute (5 = 4+1). It is the typical permission for directories and for scripts that others may run but not modify.
- Is 777 ever a good idea?
- Almost never. It lets every user on the machine write to and execute the file — the quickest way to get a web script modified or a directory trashed. Use the narrowest permission that works.
- Numeric or symbolic form — which should I use?
- They describe the same thing. Numeric (644) is compact and convenient in scripts; symbolic (u=rw,go=r) changes only the bits you mention, which is safer for small tweaks on shared files.
Category: Development
DevOps & configs workflow
Chmod Calculator — Unix File Permissions (755, 644, 777) → Crontab Generator — Cron Expressions with Plain-English Preview → Docker Run to Compose Converter — Generate a compose Service from a Command → Linux commands cheat sheet → Git cheatsheet