Number Base Converter
Convert numbers between binary, octal, decimal, and hex.
Input and custom output bases support integers from 2 to 64. 0x, 0b, and 0o prefixes are accepted as a local convenience.
Runs locally in your browser. Your input is not uploaded or stored. You can verify this in your browser’s network panel.
What does this tool solve?
Convert integers from any input base 2–64 to Binary, Octal, Decimal, Hexadecimal, Base64, and a custom output base.
What examples should you start with?
Decimal to hex
Input
255 (decimal)
Output
hex ff · binary 11111111 · octal 377
Prefixed hex
Input
0xdeadbeef
Output
decimal 3735928559
Large values
Input
2^64 = 18446744073709551616
Output
hex 10000000000000000 — exact, no float rounding
How does it work?
Input is validated against the digit set of the selected base, parsed with BigInt, and re-rendered in every output base — so arbitrarily large integers stay exact.
A 0x / 0b / 0o prefix overrides the selected base, matching the convention in most programming languages.
What are the edge cases and limits?
- Negative values convert with a leading minus sign applied to every base.
- Fractional numbers are not supported — integer bases only.
- Hex letters are case-insensitive on input, lowercase on output.
Technical reference
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