Chmod Calculator
Calculate file and directory permissions with the free Chmod Calculator. Select read, write and execute permissions for the owner, group and others to determine the matching numeric chmod value. Convert between symbolic rwx permissions and common modes such as 755 and 644. Check the target file's purpose before changing permissions, especially on shared or production servers.
| Read | Write | Execute | |
|---|---|---|---|
| Owner | |||
| Group | |||
| Others |
Permissions shown by ls -l for a regular file: -rwxr-xr--. Special bits (setuid, setgid, sticky) are not covered by this calculator.
What is Chmod Calculator?
Calculate Linux file permissions with the free Chmod Calculator. Select read, write and execute access for the owner, group and others to determine the corresponding numeric chmod value. Convert symbolic rwx permissions into numeric modes such as 755 and 644 to better understand Unix permissions. Review the file or directory's purpose before changing access, especially on shared or production servers.
Why use this tool?
- Tick the permissions you want, or type an octal mode such as 755, and see both forms.
- Shows the numeric command, the symbolic command and the permission string you see in ls -l.
- Both directions work, so you can also decode a number you found in a script.
How to use Chmod Calculator
- Step 1. Tick Read, Write and Execute for the owner, group and others, or type a three-digit octal mode.
- Step 2. Read the chmod command with the number, and the symbolic version.
- Step 3. Copy the command and replace filename with your file or directory.
Common use cases
Important notes
- Each digit is the sum of 4 for read, 2 for write and 1 for execute.
- A directory needs the execute permission before anyone can open it or list its contents with a path.
- Avoid 777 on shared or production servers because it lets every user modify the file.
- Special bits (setuid, setgid and sticky) are not covered by this calculator.
- Check what a file is used for before you change permissions, and be careful with recursive changes.
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Chmod Calculator FAQ
What does chmod 755 mean?
The owner can read, write and execute, while the group and others can read and execute. It is common for directories and scripts.
What does chmod 644 mean?
The owner can read and write, while the group and others can only read. It is common for regular files.
How is the octal number calculated?
Add 4 for read, 2 for write and 1 for execute for each class. Read and execute gives 5, and read, write and execute gives 7.
Is chmod 777 safe?
Usually not. It gives every user full access, so use a narrower mode unless you have a specific reason.
What is the symbolic form of 755?
chmod u=rwx,g=rx,o=rx filename sets the same permissions as chmod 755 filename.