Developer Tools
Chmod Calculator
Tap checkboxes for read, write, and execute across owner, group, and others to build a permission mode — or type a number like 755 and see its rwx breakdown instantly. Either way, you get the exact chmod command. All in your browser.
Special bits
Permissions
| Class | Read | Write | Execute | Octal |
|---|---|---|---|---|
| Owner | 0 | |||
| Group | 0 | |||
| Others | 0 |
Result
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chmod 000 file
What makes this tool different
Numeric to symbolic
Type 755, 644, or any three-digit mode and instantly see the rwx breakdown for each class.
Symbolic to numeric
Tap the checkboxes and watch the octal mode and chmod command build in real time.
Special bits
Understand setuid, setgid, and sticky bits and how they appear in a numeric mode.
100% in-browser privacy
Everything computes locally. Nothing you type leaves your device.
About this tool
Chmod Calculator: everything you need to know
File permissions are the first line of defense on any Linux system, and chmod is the command that controls them. Yet the octal numbers — 755, 644, 777 — are just sums of read (4), write (2), and execute (1), and mapping them to the rwx symbolic form is easy to get wrong under pressure.
This chmod calculator converts in both directions. Tap checkboxes for read, write, and execute across owner, group, and others and the numeric mode, symbolic string, and chmod command build live. Or type a mode like 755 and see the rwx breakdown for each class immediately.
Understanding common modes is the key to safe permissions. 644 (rw-r--r--) is the standard for files, 755 (rwxr-xr-x) for directories and executables, and 600 (rw-------) for private keys. The calculator makes these relationships visible instead of memorized.
Special bits are covered too. A fourth leading digit encodes setuid, setgid, and sticky bits, and the tool shows how they render symbolically as s or t — important when securing setuid binaries or shared directories like /tmp.
Whether you are fixing a broken web server, setting up SSH keys, or writing deployment scripts, the correct chmod mode matters. Generate the command here, copy it to your terminal, and ship with confidence.
Privacy is built into the design. Permission math runs entirely in your browser — nothing you type leaves your device. Open the DevTools Network tab and you will see zero requests.
FAQ
Chmod Calculator — frequently asked questions
What is chmod and what are file permissions?
chmod is the Linux/Unix command that changes file and directory permissions. Each file has three permission classes — owner, group, and others — each with read (r), write (w), and execute (x) bits. chmod sets those bits either numerically (755) or symbolically (u+x).
What does chmod 755 / 644 / 777 mean?
Each digit is the sum of read (4), write (2), and execute (1) for one class. 755 means owner has rwx (4+2+1) and group and others have r-x (4+1). 644 means owner rw- and group/others r--. 777 means everyone has rwx — usually a bad idea.
How do I convert numeric permissions to rwx symbolic form?
Convert each digit to binary: 7 is 111 (rwx), 6 is 110 (rw-), 5 is 101 (r-x), 4 is 100 (r--), 3 is 011 (-wx), and so on. The three digits map to owner, group, and others. This calculator does that conversion instantly in both directions.
What is the difference between chmod 600 and 700?
Both give the owner exclusive access — no permissions for group or others. 600 is read and write only (rw-------), while 700 adds execute (rwx------), which is needed for directories to be traversed. For private SSH keys use 600; for directories you need 700.
चामोद 776 क्या है?
chmod 776 का मतलब है मालिक (owner) के पास rwx (पढ़ना, लिखना, चलाना), समूह (group) के पास rwx, और अन्य (others) के पास rw- (पढ़ना और लिखना, लेकिन चलाना नहीं)। यानी 7+7+6, जहां 7 = 4+2+1 और 6 = 4+2 होता है।
चामोद 600 बनाम 700 क्या है?
दोनों में केवल मालिक के पास पहुंच होती है, group और others के पास कोई अनुमति नहीं। 600 का मतलब है rw- (पढ़ना और लिखना), जबकि 700 का मतलब है rwx (पढ़ना, लिखना, चलाना)। निजी SSH चाबियों के लिए 600 और निर्देशिकाओं के लिए 700 सही है।
What are special bits (setuid, setgid, sticky)?
A fourth digit can prepend special bits: 4 is setuid, 2 is setgid, 1 is sticky. setuid runs a file with the owner's privileges, setgid inherits the group, and sticky (on /tmp) prevents others from deleting your files. They appear as s or t in the symbolic form.
Why is chmod 777 risky?
777 gives everyone read, write, and execute permission, letting any user on the system modify or run the file. For directories it lets anyone delete contents. Prefer the least privilege needed, like 644 for files and 755 for directories.
Is the chmod calculator free and private?
Yes. OpenToolLab's chmod calculator is completely free, requires no signup, and computes everything in your browser — nothing is sent anywhere.
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