How to Use This Tool
Enter a Number
Type a number into the input field in any of the four supported bases.
Select the Input Base
Choose whether your number is Octal, Decimal, Binary, or Hexadecimal from the dropdown.
See All Conversions
The tool instantly shows the same number in all four bases. If the value is a valid 3-digit octal, the file permission string is shown too.
Copy Any Result
Click the copy button next to any result to put it on your clipboard.
Frequently Asked Questions
Is this tool really free?
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Yes, completely free with no limits and no sign-up. Everything runs in your browser.
Is my data sent to a server?
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No. All conversion happens directly in your browser. Nothing you type is ever sent anywhere.
What is octal?
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Octal is the base-8 number system using digits 0 through 7. It is commonly used for file permissions on Linux and Unix systems.
What are file permissions?
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When you enter a 3-digit octal value like 755, the tool shows the matching file permission string like rwxr-xr-x. Each digit controls read, write, and execute access for the owner, group, and others.
What number systems are supported?
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Four: Octal (base 8), Decimal (base 10), Binary (base 2), and Hexadecimal (base 16).
How do I convert 755 to binary?
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Select Octal as the input base and type 755. The tool shows the binary, decimal, and hex equivalents instantly.
What is chmod?
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chmod is the command used on Linux and Unix systems to change file permissions. The numbers you pass to chmod are octal values, like 755 or 644.
Does it update instantly?
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Yes. Results appear as soon as you type. No button to click.
Can I enter values in decimal or hex too?
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Yes. Switch the input base dropdown to Decimal, Binary, or Hexadecimal and the tool converts to all four bases including octal.
Does it validate input?
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Yes. If you enter digits that are not valid for the selected base, the tool shows an error message.
What Is Octal Converter?
Octal Converter is a free tool that converts numbers between octal, decimal, binary, and hexadecimal right in your browser. It also shows the file permission string for octal values, making it especially useful for anyone working with file permissions on Linux or Unix systems. Nothing you type is ever sent anywhere - all math runs locally on your device.
Enter a number in any of the four bases and see all conversions at once with copy buttons. The file permission display makes it easy to understand what chmod values like 755 or 644 actually mean.
Features Explained
Four Number Bases
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Convert between Octal (base 8), Decimal (base 10), Binary (base 2), and Hexadecimal (base 16) simultaneously.
File Permission Display
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For 3-digit octal values, the tool shows the matching Linux/Unix file permission string like rwxr-xr-x, so you can see what each digit means.
All Results at Once
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Enter a number in any base and see it in all four formats instantly. No need to convert one pair at a time.
Any Input Base
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Select your input base from the dropdown. The tool accepts octal (0-7), decimal (0-9), binary (0-1), or hex (0-9, A-F).
Copy Buttons
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Each result has its own copy button so you can grab the value you need in one click.
Instant Conversion
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Results update live as you type. No Convert button needed.
Input Validation
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If you enter digits that are not valid for the selected base, the tool shows an error message.
Permission Breakdown
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The file permission display shows read (r), write (w), and execute (x) for owner, group, and others, making chmod values easy to understand.
Large Number Support
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The tool handles numbers of any size your browser can process, not just small values.
100% Browser-Based
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All conversion runs directly in your browser. Nothing you type is ever sent to any server.
Who Is This Tool For?
Linux System Administrators
Convert chmod permission values between octal, binary, and the rwx permission string.
DevOps Engineers
Verify file permission settings in deployment scripts and configuration files.
Web Developers
Set correct file permissions for web servers, uploads directories, and configuration files.
Computer Science Students
Learn octal and practice converting between number bases for coursework and exams.
Teachers
Demonstrate octal conversions and file permissions in real time during lessons.
Programmers
Convert between octal, hex, and binary when working with bitwise operations and data encoding.
Security Analysts
Verify and audit file permissions by converting between octal and the readable rwx format.
Unix Administrators
Quickly look up what chmod values like 755, 644, or 600 mean in terms of actual permissions.
Cloud Engineers
Set correct container and volume permissions by converting between octal and permission strings.
Database Administrators
Convert file permission values when setting up database directories and log files.
Embedded Developers
Convert between octal and other bases for register values and configuration settings.
Network Engineers
Convert ACL and permission values between octal and binary.
IT Support
Troubleshoot file access issues by understanding what permission numbers actually mean.
Shell Script Writers
Verify chmod values in scripts by converting to the readable permission string.
Docker Users
Set correct file permissions in Dockerfiles and container configurations.
Game Developers
Convert between number bases for asset management and file system operations.
Data Engineers
Set correct permissions on data pipeline directories and output files.
QA Engineers
Verify file permissions in test environments match production specifications.
Researchers
Convert between number bases for data analysis and scientific computing.
Hobbyists
Learn about octal, file permissions, and number base conversions for personal projects.
Backup Administrators
Verify that backup file permissions are correct by converting octal values.
WordPress Administrators
Fix file permission issues by understanding what 755 and 644 mean for directories and files.
Freelancers
Set correct server permissions when deploying client websites and applications.
Anyone
Quickly convert any number between octal, decimal, binary, and hex for any reason.
Tips for Best Results
Common chmod values
755 = rwxr-xr-x (directories), 644 = rw-r--r-- (files), 600 = rw------- (private files), 777 = rwxrwxrwx (full access, use with caution).
Each octal digit = 3 permission bits
The first digit is owner, second is group, third is others. Each digit is the sum of read (4), write (2), and execute (1).
7 = rwx, 5 = r-x, 4 = r--
7 means read+write+execute. 5 means read+execute. 4 means read only. 0 means no access.
Octal to binary is simple
Each octal digit maps to exactly 3 binary bits. 7 = 111, 5 = 101, 0 = 000. Convert one digit at a time.
Use for server setup
Web servers typically need 755 for directories and 644 for files. This tool shows you exactly what those numbers mean.
Copy any result
Click the copy button next to any base to grab that value without selecting it manually.
Results update instantly
Change the input and all four bases recalculate immediately.
Input validation protects you
If you type digits outside the valid range for your selected base, the tool tells you instead of giving a wrong answer.
Hex and octal together
Octal and hex are both shortcuts for binary. Each octal digit = 3 bits, each hex digit = 4 bits.
Privacy is built in
Nothing you type is ever sent to any server. All conversion runs in your browser.
Privacy & Security
This tool runs 100% in your browser. Your files stay entirely on your own device. Nothing is uploaded, nothing is shared, and no server, advertiser, or third party has access to your files.
If a tool saves your work on your own device, you can remove it at any time using the Clear All button. Some tools rely on an external service to return their result; in those cases, only the minimum data required for the request is sent, and never your files or content. Any ads shown on this page run in an isolated frame and cannot read, touch, or transmit anything you upload, paste, type, or download here. Advertisers may see standard visit information like your IP address and which page you're on, as described in our Privacy Policy, but your data itself stays fully under your control.
