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Decimal to Octal
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Decimal · base 10
Hexadecimal · base 16
Binary · base 2
Octal · base 8
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Enter a decimal value above to convert it
// about this tool

Decimal to Octal Online

Updated 2026-10-24

Convert decimal to octal online for free. Type any base-10 number and SnapTools shows its octal value instantly, in your browser. Nothing you enter is uploaded.

Going from a plain integer to octal is most useful when the number represents a Unix permission bitmask: 493 only becomes recognizable once you see it as 755. This converter runs the repeated-division-by-8 for you and returns clean octal digits, ready to use with chmod, umask, or any tool that expects base-8 notation. For every base at once, use the Number Base Converter.

// how to use

  1. 1 Type or paste a decimal (base-10) number into the input.
  2. 2 SnapTools converts it to octal as you type.
  3. 3 Copy the octal result, or open the Number Base Converter for all bases at once.

// examples

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

// common uses

Converting a plain integer permission value into a chmod-style octal value Producing octal literals for legacy C or POSIX code Learning base-8 positional notation Checking a manual decimal-to-octal conversion

// faq

Why is the Unix command for viewing raw file bytes called "od"?
It stands for "octal dump." The command dates to Bell Labs in 1971, when octal was the standard way to read raw file bytes on early Unix systems, and the name survived even though od now also supports hex and decimal output.
How do I convert decimal to octal by hand?
The manual method is short division by 8. Divide, note the remainder, divide the quotient again, and stop once the quotient reaches zero. Reading those remainders in reverse gives the octal digits; for 493 that produces 7, 5, 5, or 755.
Why would I want a decimal number as octal?
The most common case is turning a plain integer permission value into the octal form Unix tools like chmod expect; 493 as a permission bit isn't meaningful until you see it as 755.
Does the output use a leading 0?
No, this tool returns the plain octal digits without an old-style leading 0 prefix. Add one yourself if your target format requires it.
What is the largest number it handles?
Regular whole numbers pose no problem here; precision only becomes a factor once a value is large enough to exceed the safe-integer boundary that ordinary floating-point arithmetic can represent exactly.

// works with your data

Octal to Decimal Decimal to Hex Decimal to Binary Number Base Converter Hex to Octal Remove Duplicate Words

Use this via API

Get a free API key → 
curl -X POST https://thesnaptools.com/api/v1/tools/decimal-to-octal \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"number":"493"}'