Number Base Converter
Convert an integer from one number base to another in your browser — pick a source base and a target base from 2 to 36, with one-click presets for binary, octal, decimal, and hexadecimal.
Integers only (zero, positive, negative). Values use arbitrary-precision integers, so digits beyond 2^53 are kept exactly. Leading zeros are not preserved and output digits are uppercase. Standard 0b / 0o / 0x prefixes are accepted only when they match the source base.
How to use it
- Enter the integer to convert (for example 255, -FF, or 0b1010)
- Choose the source base and the target base, from 2 to 36 or a preset
- Click Convert to get the uppercase result in the target base
- Copy the result, use Swap to reverse the two bases, or Clear to start over
Values are handled as arbitrary-precision integers with BigInt, so digits far beyond 2^53 stay exact and every conversion round-trips without loss. Negative integers are supported and written with a leading minus sign; a leading plus is accepted for symmetry. Digits are checked against the source base before conversion, so an 8 in octal or a G in hexadecimal is reported rather than silently accepted, and input is case-insensitive while the result is uppercase. Standard 0b, 0o, and 0x prefixes are accepted only when they match the base you selected — a mismatched prefix is rejected, never auto-detected. Leading zeros are not preserved, and this tool converts integers only: decimal fractions, scientific notation, and thousands separators are refused. Everything runs locally in your browser, so the number you enter is never uploaded or stored. This is different from a Base64 Encoder, which encodes bytes or text, and from a Hex Viewer, which lists the raw bytes of a file rather than converting a numeral.
FAQ
Any base from 2 to 36, using the digits 0-9 then A-Z. One-click presets cover binary (2), octal (8), decimal (10), and hexadecimal (16).
Yes. The value is stored as an arbitrary-precision BigInt, so integers with hundreds or thousands of digits convert exactly, well beyond the 2^53 limit of ordinary numbers.
Yes. A leading minus sign is accepted and preserved in the result; a leading plus is also accepted for symmetry. Negative zero is normalised to plain zero.
No. Version 1 handles integers only. Decimal points, scientific notation like 1e10, and thousands separators are rejected with a clear message rather than rounded.
No. The conversion runs entirely in your browser with no network request and no storage; only an anonymous tool-usage event, without your input, is recorded.