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Chmod Calculator — File Permissions Made Simple

Click the checkboxes to set read, write, and execute for owner, group, and others. Get the numeric value (like 755), the symbolic form (rwxr-xr-x), the exact chmod command, and a plain-English explanation — instantly.

Set permissions

ReadWriteExecute
Ownerrwx
Grouprwx
Othersrwx

Special bits

Result

Numeric
755
Symbolic
rwxr-xr-x
chmod 755 my-file.txt

Warning: 777 is dangerous.Everyone can read, write, and execute this file — including running it as a program and replacing its contents. On a shared or public server this is a serious security risk. Use 644 for files or 755 for folders/scripts instead.

100% private

The whole calculator runs in your browser. Nothing is uploaded, tracked, or stored on any server.

No signup

No account, no email, no download. Open the page and start clicking.

Free forever

Unlimited permission calculations, presets, and explanations — free with no hidden limits.

How to use the chmod calculator

  1. 1Click the checkboxes

    Set read, write, and execute for owner, group, and others in the 3×3 grid — or enable the special bits below it.

  2. 2Read the result

    The numeric value, symbolic form, and the exact chmod command update live. The plain-English box explains who can do what.

  3. 3Copy the command

    Type your file or folder name, hit "Copy command", and paste it straight into your terminal or SSH session.

Why use this chmod calculator

Live numeric and symbolic output

Every click recomputes the octal value (like 755), the symbolic form (rwxr-xr-x), and the ready-to-paste chmod command at the same time.

Plain-English explanations

No more guessing what 644 means — the tool tells you in words exactly what the owner, group, and others can and cannot do.

Special bits included

Setuid, setgid, and the sticky bit are built in, with correct 4-digit values (like 4755) and s/S/t/T symbolic notation.

Common presets in one click

Jump straight to 644, 755, 600, 777, or 640 — the permissions you will use for web files, scripts, private keys, and folders.

777 danger warning

If you build 777, the calculator warns you loudly: everyone gets full control, which is almost never what you want.

Copy-paste ready commands

Type the file name once and every result is formatted as a real terminal command you can copy into SSH or a local shell.

Chmod FAQs

What do the numbers in chmod mean?
Each digit is a sum: read = 4, write = 2, execute = 1. So 7 means read, write, and execute (4+2+1), 6 means read and write (4+2), 5 means read and execute (4+1), and 4 means read only. The three digits stand for owner, group, and others — so 755 gives the owner full control and everyone else read plus execute.
When should I use 755 vs 644?
Use 755 for folders and executable scripts (owner can do everything; everyone else can read and execute). Use 644 for regular files like HTML, images, and CSS (owner can read and write; everyone else can only read). Most shared hosting setups expect exactly this split.
Is 777 ever safe to use?
Almost never. 777 lets every user on the system read, modify, and execute the file. It is a common fix for "permission denied" errors, but it masks the real problem — usually wrong file ownership — and opens a serious security hole. This calculator warns you whenever 777 is selected.
What are setuid, setgid, and the sticky bit?
Setuid (4000) makes a program run with the file owner's privileges; setgid (2000) runs it with the group privileges, or makes new files in a folder inherit the folder's group; the sticky bit (1000) on a folder means only a file's owner can delete it — the classic /tmp behavior. They add a leading fourth digit, like 4755.
What does the symbolic form like rwxr-xr-x mean?
It is the same permission in letters: three groups of rwx for owner, group, and others, with a dash where access is denied. So rwxr-xr-x = owner can do everything (rwx), group can read and execute (r-x), and others can read and execute (r-x) — exactly 755.
How do I change permissions on all files in a folder?
Use the recursive flag: chmod -R 755 folder-name applies the permission to the folder and everything inside it. Be careful — combining -R with 777 will open up every file at once.
Why does my web host say files should be 644?
Because your website's files only need to be readable by the web server, not writable or executable by strangers. 644 (rw-r--r--) gives you read/write and everyone else read-only, which is the secure default for web content.

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