Convert numbers between any bases from 2 to 36, with binary, octal, decimal and hexadecimal shown alongside.
Bases other than 2, 8, 10, 16 and 36 are supported by the maths — the dropdown lists the common ones, and the value is converted exactly with big integers, not floating point. This is arbitrary-base conversion, not the binary-arithmetic tool.
converted value
How to use this tool
Enter the number in its source base, using digits 0–9 and letters A–Z for values above 9.
Pick the source base and the target base. Common bases are listed; the maths handles any base from 2 to 36.
The headline is the number in the target base, with binary, octal, decimal and hexadecimal equivalents alongside.
A digit must be smaller than the source base: F is valid in hexadecimal but not in decimal, and 2 is not a binary digit.
Formula & worked example
FF in hexadecimal is 15 × 16 + 15 = 255 in decimal, 11111111 in binary and 377 in octal.
Limitations — read this before you rely on it
Only whole numbers are converted; fractional parts in other bases need a separate digit-by-digit expansion and are not covered. Very long inputs are handled exactly with big integers, but there is no practical limit a browser page should need.
Frequently asked questions
The number of distinct digits a counting system uses. Decimal uses 10 digits, binary uses 2, hexadecimal uses 16.
Because base 16 needs 16 digits. After 0–9, the letters A–F stand for values 10–15.
Convert to decimal first by weighting each digit by its place value, then convert out of decimal by repeated division, reading remainders backwards.
No. That tool does binary arithmetic and the common conversions. This tool converts between any two bases from 2 to 36.
No, only whole numbers. Fractions in another base are a different calculation and are not included here.