Octal to Decimal Converter

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Check Out The Full Number Base Converter Tool
Installable as PWA

Convert octal to decimal (base 8 → base 10)

Use this converter when you have octal integers (base 8) and need the decimal value (base 10).

This page is a focused Octal → Decimal variant built for speed:

Batch mode is enabled by default (one value per line)
Controls are intentionally hidden to keep this variant fast and distraction-free

Need binary/hex too, swapping, or formatting options? Open the full Number Base Converter.

How to use it

Paste your octal values into the input (left).
Use one number per line.
Copy the decimal results from the output (right).

Signed values are supported:

-11 → -9
+377 → 255

Input rules (octal)

Allowed digits

Octal input may contain only:

digits 0–7
an optional leading + or -

Examples:

0
7
10
755
-52

Optional 0o prefix

You may paste values like:

0o755
-0o52

Separators are ignored

Spaces and underscores are ignored, so these are valid:

7_55
0o7 55

Output format (decimal)

Output is a base-10 integer
Negative values keep a leading -

Examples:

10 → 8
11 → 9
52 → 42
377 → 255
2000 → 1024
-52 → -42

Batch example (one per line)

Input (octal):

Output (decimal):

8
9
255
-42
493
!ERROR: Octal input may contain only digits 0–7

One invalid line won’t break the rest.

Common use cases

Unix file permissions

Permissions are often written in octal (e.g. 755, 644). Converting to decimal can help when you’re debugging systems that store permission masks as integers.

Binary-friendly grouping

Because each octal digit corresponds to 3 bits, octal can be more readable than long binary strings while still mapping cleanly to bit patterns.

Learning number bases

Octal is a great stepping stone between binary and decimal, especially in digital electronics.

Troubleshooting

“Octal input may contain only digits 0–7”

A line includes an invalid digit (like 8 or 9) or letters.

Remove invalid characters, or switch to the full tool if your input isn’t actually octal.

“Is 0755 octal?”

Some contexts treat leading zeros as octal, but that depends on the language/tool.

Here, you can paste 755 (or 0o755) and convert it consistently.

Notes

This is number base conversion for integers, not text/byte encoding.
Everything runs locally in your browser — nothing is uploaded.

Frequently Asked Questions

Does this support negative octal numbers?

Yes. Use a leading minus sign (−) or plus sign (+). The sign is preserved in the decimal output.

Can I convert multiple octal values at once?

Yes. This variant runs in batch mode by default: paste one octal integer per line and get one decimal result per line.

Can I paste values with a 0o prefix?

Yes. Inputs like 0o755 are accepted in this variant.

Does it accept spaces or underscores in octal?

Yes. Spaces and underscores are ignored, so values like 7_55 or 0o7 55 work.

Why is octal used at all?

Octal maps cleanly to binary (each octal digit = 3 bits), and it’s commonly used for Unix-style file permissions.

Try one of our format-specific converters below

Binary to Decimal Converter

Convert signed binary integers (base 2) to decimal (base 10) instantly. Batch mode is on by default (one number per line), supports +/− values, optional 0b prefixes, and runs locally in your browser.