snaptools
chain
⇄
Octal to Decimal
⌃⏎ run · ⎋ clear · / focus input
Decimal · base 10
send result to
no matches
Hexadecimal · base 16
Binary · base 2
Octal · base 8
Enter a octal value above to convert it
// about this tool

Octal to Decimal Online

Updated 2026-07-26

Convert octal to decimal online for free. Paste an octal value and SnapTools shows its decimal (base-10) value instantly, right in your browser. Nothing you enter is uploaded.

Octal notation is most familiar from Unix file permissions (chmod 755), but some tools and APIs expect that same value as a plain base-10 integer instead. This converter runs the base-8 positional arithmetic for you — multiplying each digit by the right power of 8 — so you get the exact decimal equivalent without doing it by hand. For every base at once, use the Number Base Converter.

// how to use

  1. 1 Paste or type an octal (base-8) value into the input — digits 0-7 only.
  2. 2 SnapTools converts it to decimal as you type.
  3. 3 Copy the decimal result, or open the Number Base Converter for all bases at once.

// examples

Common file permission
Input
755
Output
493
Byte value
Input
377
Output
255

// common uses

Converting a Unix permission value (chmod 755) into its plain integer form Reading legacy octal literals from C or POSIX code as ordinary numbers Checking a manual octal-to-decimal conversion Learning base-8 positional notation

// faq

Is my input uploaded to a server?
No. The conversion runs entirely in your browser, so nothing you enter leaves your machine.
How do I convert octal to decimal by hand?
Multiply each digit by 8 raised to its position (counting from 0 on the right) and add the results. For 755 that's 7×64 + 5×8 + 5×1 = 448 + 40 + 5 = 493. This tool does the arithmetic for you.
Why would I want a permission value like 755 in decimal?
Some APIs and file-metadata tools store or report Unix permission bits as a plain integer rather than the usual octal notation, so converting a familiar chmod value to decimal is a common lookup.
Does it accept a leading 0 (like old-style octal literals)?
Yes — a leading 0 is just an extra digit and is safely ignored by the conversion; you do not need to strip it first.
What if my input has an 8 or 9 in it?
Octal only uses digits 0-7. An 8 or 9 is flagged as invalid, since it cannot represent a real octal digit.

// works with your data

Sort & Dedupe Lines Slug Generator Reverse Text Text Repeater Remove Duplicate Lines Whitespace Remover

Use this via API

Get a free API key → 
curl -X POST https://thesnaptools.com/api/v1/tools/octal-to-decimal \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"number":"755"}'
Esc
↑↓ navigate ↵ open Esc close