Chmod Calculator Online — Linux Permission Generator
Calculate Linux/Unix chmod numeric and symbolic permissions with checkboxes. Common presets included.
| Permission | Read (r=4) | Write (w=2) | Execute (x=1) | Octal |
|---|---|---|---|---|
| Owner | 7 | |||
| Group | 5 | |||
| Others | 5 |
Common presets
Click any preset to apply, or toggle the checkboxes above.
How to Use Chmod Calculator
- 1
Click the checkboxes for read (r), write (w), and execute (x) under Owner, Group, and Others.
- 2
The numeric value (e.g. 755) and symbolic notation (e.g. rwxr-xr-x) update instantly.
- 3
Copy the value or pick a common preset like 755, 644, or 600.
About Chmod Calculator
Calculate Linux and Unix file permissions instantly with our free online chmod calculator. Toggle read, write, and execute for owner, group, and others, and immediately see both the numeric chmod value (like 755 or 644) and the symbolic notation (like rwxr-xr-x). Everything runs in your browser via simple bitwise math. **Why developers use chmod calculators** chmod is one of those Unix commands you use just often enough to forget exactly how it works. Is 755 the right value for an executable? What does the third digit mean? Is 600 secure enough for an SSH private key? A visual calculator removes the mental math and prevents subtle bugs. **Common permission values** - **755** (rwxr-xr-x): Standard for directories and executable files. Owner has full control, everyone can read and execute. - **644** (rw-r--r--): Standard for regular files. Owner can edit, everyone can read. - **600** (rw-------): Private file. Only the owner can read or modify. Required for SSH private keys. - **700** (rwx------): Private directory. Only the owner can access. Used for .ssh directories. - **777** (rwxrwxrwx): Full access for everyone. Almost always wrong outside of debugging. - **664** / **775**: Group-writable variants used in team environments where multiple users edit shared files. **The numeric formula** Each digit is the sum of three bits: read (4) + write (2) + execute (1). So 7 means all three (4+2+1), 5 means read and execute (4+1), 6 means read and write (4+2). The three digits represent owner, group, and others, in that order. **Special considerations** - Directories need the execute bit to be entered. A directory with permission 644 cannot be listed, even by its owner. - The setuid, setgid, and sticky bits are advanced and not included in this calculator. Most users never need them. - Web servers often expect specific permissions: 644 for files and 755 for directories. PHP applications usually fail with 777 because the server refuses to execute world-writable files.
Built by
Fateh Raiyan IshmumFull-stack dev since 2020. Full-stack web developer since 2020. Builds privacy-first, open-web tools. Specialises in Next.js, TypeScript, and performance-focused design.
Frequently Asked Questions
chmod 755 gives the owner read, write, and execute (rwx = 4+2+1 = 7), and gives the group and others read and execute only (r-x = 4+0+1 = 5). This is the standard for directories and executable files. Use it for scripts, web directories, and binaries that everyone should be able to run but only the owner can modify.
chmod 644 gives the owner read and write (rw- = 4+2 = 6), and gives group and others read only (r-- = 4). This is the standard for regular files like text documents, HTML, CSS, and images served from a web server.
chmod 777 grants read, write, and execute permission to everyone — owner, group, and others. It is almost always wrong on a real system. It means any user can modify or delete the file. Never use 777 in production unless you fully understand the security implications.
Numeric uses three digits (e.g. 755) where each digit is the sum of read (4) + write (2) + execute (1). Symbolic uses letters (e.g. rwxr-xr-x) where r=read, w=write, x=execute, and a dash means no permission. Both forms represent the same permission; numeric is faster to type, symbolic is easier to read.
The 9 characters are three groups of three: owner permissions, group permissions, others permissions. So rwxr-xr-- means owner can read/write/execute, group can read/execute, and others can read only. A dash means no permission. The first character (sometimes shown as d, l, or -) indicates the file type, but the chmod value itself is just the 9 permission characters.
No. This calculator runs entirely in your browser using simple bitwise math. Nothing is uploaded, logged, or stored.