Non-hex digits
Only characters 0-9 and A-F are allowed.
Fix: Check the input for typos or non-hex letters.
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.
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What is Hex to Octal Converter
Last reviewed:
Hexadecimal (base 16) uses digits 0-9 and letters A-F to represent bytes compactly, widely used for colors, hashes, and low-level binary data.
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
755
Common errors
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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Convert hexadecimal to decimal
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Octal to Decimal
Convert octal to decimal
Decimal to Octal
Convert decimal to octal
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