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Decimal to Octal
About This Tool
Decimal to Octal is a free daily-quota online decimal to octal converter that requires no installation and no registration — ready to use in seconds. Enter decimal or octal numbers and convert them in both directions with a single click, with support for batch conversion, copy and download. All processing is done locally in your browser for 100% privacy — your data is never uploaded to any server. Whether you are setting Linux permissions, configuring networks or learning programming, this tool delivers accurate, professional-grade results effortlessly.
How to Use
- Enter numbers
Type decimal or octal (0-7) numbers in the left input box. Separate multiple numbers with spaces, commas or new lines
- Pick direction
Click the "Decimal → Octal" or "Octal → Decimal" button and the conversion happens automatically
- View result
The result appears in the right text box. Use the "Copy" or "Download" button to save it
Use Cases
- Permission settings: the chmod command in Linux/Unix uses octal numbers for file permissions — convert permission values in a snap
- System configuration: some network devices and system configs store values in octal; converting them makes them easier to understand
- Programming learning: quickly verify conversions while studying octal literals in languages like C/C++ and assembly
Key Advantages
- Free Daily Quota
Every day you get free usage, which is enough for light everyday needs at zero cost. Frequent or professional users can unlock higher quotas with a membership
- Privacy Safe
All conversions run locally in your browser — data is never uploaded to any server, so sensitive content stays completely private
- No Install, No Sign-up
Open the page and start converting right away — no software to download and no account to register
- Batch Conversion
Convert multiple numbers at once by separating them with spaces, commas or new lines, with results output one-to-one in order
- Accurate and Reliable
Strictly follows standard base-conversion rules, auto-detects the
0oprefix and validates input for error-free results - Works on All Devices
Runs smoothly on desktop, mobile and tablet — just open your browser, regardless of operating system
Common Value Reference
Here are the decimal-octal pairs used most often in development and operations, so you can quickly grasp the conversion pattern:
| Decimal | Octal | Note |
|---|---|---|
| 7 | 7 | Largest single-digit octal number |
| 8 | 10 | Carries over to two digits |
| 9 | 11 | Octal representation of 9 |
| 10 | 12 | Octal representation of 10 |
| 16 | 20 | Octal representation of 16 |
| 32 | 40 | Octal representation of 32 |
| 64 | 100 | Octal representation of 64 |
| 511 | 777 | Maximum value of a 3-digit octal number |
Unix File Permissions
On Linux/Unix systems, file permissions are written as a three-digit octal number. For example, 755 means the owner can read, write and execute (7), the group can read and execute (5), and others can read and execute (5).
Each octal digit stands for one permission set: 4 for read, 2 for write and 1 for execute — add them together to get the value. Use this tool to convert common decimal permission values into octal quickly.
FAQ
A decimal to octal converter is an online base-conversion tool. It converts decimal integers to octal and back, supports batch processing of multiple values at once, and runs entirely in your browser with no data upload.
It takes just three steps. First, type decimal or octal numbers into the left input box. Next, click the matching conversion button (e.g. "Decimal → Octal"). The result instantly appears in the right text box, which you can save with the "Copy" or "Download" button.
Both decimal and octal are supported, including common prefixes. Octal numbers may use the 0o prefix (e.g. 0o17), plain numbers without a prefix work fine too, and multiple values can be separated by spaces, commas or new lines.
Batch conversion is fully supported. Separate values with spaces, commas or new lines and the tool converts them one by one with matching outputs. Free usage is granted every day; high-frequency or large-volume needs can be unlocked with a membership.
Conversion is instant. All calculations run locally in your browser, so there is no server waiting time — even large batches return results immediately.
Completely safe — data never leaves your device. Everything is processed locally in your browser and no data is uploaded to any server, so there is zero risk of data leaks. Feel free to convert sensitive content.
No sign-up required — use it right away. Every day you get a free quota that covers light everyday needs at zero cost. If you need a higher quota or more frequent use, a membership unlocks additional benefits.
Yes, it works on all platforms. The tool adapts to desktops, phones and tablets — just open it in your browser for a smooth conversion experience, with no app installation needed.
Faster, more accurate and more convenient. Manual decimal-octal conversion is error-prone, and ordinary calculators struggle with batches. This tool offers one-click batch conversion, automatic input validation, and copy/download support — far more efficient than doing it by hand.
Check your input for illegal characters. Decimal input may contain only digits, and octal numbers may contain only 0-7. Also make sure multiple values are separated by spaces, commas or new lines, then retry the conversion.
Octal is commonly used for file permissions. On Linux/Unix, the chmod command sets permissions with a three-digit octal number such as 755 or 644, where each digit is the sum of read (4), write (2) and execute (1). This tool converts between the values quickly.
Absolutely. This site also offers decimal-binary, decimal-hex and binary-octal converters, so you can combine them as needed to convert freely between multiple bases.
Content last updated：2026-07-10
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