Hex to Octal Converter

Convert a hexadecimal number into its octal representation for file permissions, legacy protocols, and bitmask debugging.

Quick Converter

Use a compact field for small conversion and calculation tools.

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 Hex to Octal Converter

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

Hex to Octal Converter parses a hexadecimal value (with or without a 0x prefix) and returns the equivalent octal representation as a plain string.

This is commonly needed when working with Unix file permissions that happen to be displayed in hex, inspecting CPU registers, or cross-checking bitmask tables that list values in multiple bases.

Why use it

Translate hex bitmasks into octal file permissions (e.g. 0x1ED -> 0755).
Compare CPU register values across manuals that mix bases.
Audit embedded firmware that logs values in different bases.
Cross-check manual base conversions during debugging.
Teach students how octal and hex relate via binary.

Features

Case-insensitive hex parsing
Optional 0x prefix handling
Instant octal output
Client-side conversion
Copy-ready result

How to use Hex to Octal Converter

Paste the hex value. Drop a hex number (with or without 0x) into the input.
Read the octal. The octal equivalent appears in the output panel.
Copy the result. Use the copy button to paste the octal into code or notes.

Example (before/after)

Hex input

1ED

Octal output

Common errors

Non-hex digits

Only characters 0-9 and A-F are allowed.

Fix: Check the input for typos or non-hex letters.

Extremely large numbers

Values exceeding JavaScript's safe integer range lose precision.

Fix: For very large numbers, use a BigInt-aware tool instead.

Missing 0x prefix on input that needs it

If you feed the output to a C or Python literal, octal needs a 0o or leading 0.

Fix: Prepend 0o as needed when pasting the result into code.

FAQ

Can I include the 0x prefix?

Yes. The tool strips it automatically.

Is it case-sensitive?

No. Hex letters can be upper or lower case.

Does the tool preserve leading zeros?

Leading zeros are removed because they have no numeric value. Re-add them manually if a format requires them.

What is the maximum value?

Up to 2^53 - 1 due to JavaScript number precision.

Is conversion done in the browser?

Yes, entirely client-side.

How do I reverse it?

Use the Octal to Hex tool.

Related tools

Combine hex to octal with the wider base-conversion toolset. You can also browse the full Unit Converters category for more options.

Octal to Hex Converter

Convert an octal number into its uppercase hexadecimal form for cross-base arithmetic and register inspection.

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