Octal to Decimal

Convert octal to decimal

Octal to Decimal

Convert octal digits to a decimal number.

Input

Focused controls for small conversions and calculations.

Value

Results

Readable cards for unit-heavy output, with raw output kept for special cases.

Enter a value above or tap a sample to see structured results.

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What is Octal to Decimal

Written by Giorgos Kostas. Last reviewed: April 18, 2026

Octal to Decimal converts a base-8 number such as 755 into its base-10 value, making legacy numeric notation easier to compare with modern decimal output.

Developers usually hit octal while reading Unix permissions, old protocol docs, or number-base exercises. Converting the value makes it clear whether the octal digits represent a number, a permission mask, or text encoded somewhere else.

Why use it

Translate Unix-style permission values into decimal numbers.
Check base-conversion homework or interview examples.
Debug legacy formats that still document values in octal.

Features

Converts base-8 numbers to base-10
Rejects invalid octal digits
Useful for Unix permissions and legacy specs
Runs entirely in the browser

How to use Octal to Decimal

Enter an octal number. Paste a base-8 value that uses only digits 0 through 7.
Convert. Run the converter to calculate the decimal value.
Check the context. Use the result as a numeric value, or switch to an octal decoder if the input represents bytes.

Example (before/after)

Octal input

Decimal output

Common errors

Using 8 or 9 in octal input

Octal numbers only use digits 0 through 7.

Fix: Remove invalid digits or confirm that the source number is actually decimal.

Confusing numeric octal with text encoding

Octal byte escapes and octal numbers are related but not the same workflow.

Fix: Use Octal Decoder when you need to turn octal byte groups back into text.

FAQ

Why does octal 755 equal decimal 493?

Octal 755 means 7 x 64 plus 5 x 8 plus 5, which totals 493 in decimal.

Can octal numbers contain 8 or 9?

No. Base 8 uses only digits 0 through 7, so 8 and 9 make the input invalid.

Is this the same as decoding octal text?

No. This converter handles numeric base conversion. Use an octal decoder for byte groups that represent text characters.

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Pair octal conversion with binary, decimal, and text encoding tools. You can also browse the full Number & Bitwise Tools category for more options.

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