Number Base Converter
Convert numbers between decimal, hexadecimal, binary, and octal instantly.
All conversions happen in your browser. No data is sent to our servers - see why that matters. Share links encode your input in the URL itself; nothing is stored on a server. Press Cmd/Ctrl + Enter to convert.
How to Convert Number Bases
Enter a number in any supported base and the converter shows it in decimal, hexadecimal, binary, and octal simultaneously. Prefixes are auto-detected: 0x means hex, 0b means binary, 0o means octal, and unprefixed digits are decimal.
Why Developers Convert Bases
Hex is the language of memory addresses, color codes, and byte dumps; binary reveals bit flags and permissions masks; octal appears in Unix file modes like 755. Converting between them is everyday work when debugging low-level code or reading protocol specs.
Frequently Asked Questions
What input formats are accepted?
Plain decimal (255), hex with 0x prefix (0xff), binary with 0b prefix (0b11111111), octal with 0o prefix (0o377), and bare hex containing letters (ff). Underscore separators like 1_000_000 are ignored.
How large can the numbers be?
Arbitrarily large. The converter uses big-integer arithmetic, so 128-bit hashes, IPv6 addresses as integers, and other huge values convert exactly with no precision loss.
Can I convert several numbers at once?
Yes. Enter one number per line and each converts independently.
Are negative numbers supported?
Yes, with a leading minus sign. The output shows the sign in every base (two's complement is not applied).
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