Number Base Converter
🔒 Runs in your browser
Results
Arbitrary base
Edit any field — the others recompute. Digits 0-9 then A-Z, up to base 36.
How the base converter works
Type a number, pick the base it is written in, and its binary, octal, decimal and hexadecimal
forms appear at once — plus any base from 2 to 36 in the arbitrary-base row. Every field is
editable: change the decimal value and the others follow, or paste a hex string and read off the
binary. Digits run 0-9 then A-Z, so base 16 uses A–F and base 36 uses
the whole alphabet.
Big numbers stay exact
Conversion is done with BigInt, not floating-point, so there is no 253
ceiling. A 64-bit identifier, a 128-bit UUID written as a number, or a 2100 value all
convert digit-for-digit with nothing rounded away. Negative numbers (a leading -)
and 0x, 0b, 0o prefixes matching the selected base are
understood too.
Everything runs in your browser
The math happens locally on your device — nothing you type is uploaded or stored. If a character is not a valid digit for the chosen base, the field is flagged and the message names the culprit, so a stray 2 in a binary number or a G in hexadecimal is caught immediately.
Frequently asked questions
Does it handle very large numbers?
Yes. Conversion uses BigInt, so integers far beyond 2^53 (JavaScript’s safe limit) are exact — 64-bit values and larger round-trip without losing a single digit.
Which bases are supported?
Any base from 2 to 36. Binary, octal, decimal and hexadecimal are always shown; the arbitrary-base row covers everything in between, using 0-9 then A-Z as digits.
Can I paste values with a 0x, 0b or 0o prefix?
Yes. A prefix matching the selected base is accepted and stripped automatically. A leading minus sign for negative numbers works too.
What happens with an invalid digit?
The converter flags the field and tells you which character is not valid for the chosen base — for example the digit 2 in binary, or the letter G in hexadecimal.