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Octal to Decimal Converter

Convert a base-8 octal value into a plain decimal number, whether you are decoding file permissions or an old-style number literal. Everything runs locally in your browser.

=
255

Octal (base 8) in, Decimal (base 10) out.

How it works

Multiply each digit by 8 raised to its position from the right and add: 52 = 5×8 + 2 = 42.

Examples

FAQ

How do I convert octal to decimal?

Multiply each digit by 8 raised to its position from the right and add: 52 = 5×8 + 2 = 42. Or just paste your octal value into the box above and the decimal result appears instantly.

Does this Octal to Decimal converter run in my browser?

Yes. The conversion happens entirely client-side — nothing you type is uploaded — and it uses big-integer math, so even very long octal numbers convert exactly.

What is the largest number I can convert?

There is no practical limit. Because the converter works with arbitrary-precision integers, a octal value of any length converts without rounding or overflow.

Need other bases, custom radixes, or two-way editing? Use the full Number Base Converter.

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