About this number base converter
Enter an integer, pick its base (2/8/10/16, or any base between 2 and 36) and get the binary, octal, decimal and hexadecimal representations at once. Output is formatted for readability: binary is grouped in 4-bit blocks, decimal gets thousands separators, hex is uppercase — each with a one-click copy button.
The value is parsed with parseInt and then re-serialized back to the input base for verification, so strings like "129" that cannot exist in octal are rejected outright; negative numbers and decimals are not supported, nor are values beyond JavaScript's safe integer range. Conversion happens entirely in your browser.