Number Base Converter — Free Online Tool

The Number Base Converter translates values between binary, octal, decimal, and hexadecimal.

Each base exists because it fits a particular job. Binary is what hardware actually uses, since a bit is a physical state. Hexadecimal is the practical way to read binary, because one hex digit maps exactly onto four bits — so a byte is always exactly two hex characters, which makes memory dumps, colour values, and byte-level data readable in a way a long binary string is not. Octal maps onto three bits and survives mainly in Unix file permissions, where 755 and 644 are three-bit permission triples rather than arbitrary numbers.

The conversions turn up constantly once you know where to look. CSS colours are three hex bytes. MAC addresses, memory addresses, and hash digests are hex. Bitmask flags and subnet masks make sense in binary and look arbitrary in decimal. Character codes and escape sequences appear in hex or octal depending on the convention in use.

Two details worth knowing. Hex digits above 9 use letters A through F for 10 through 15, and case is not significant. And the same digit sequence means different values in different bases — 100 is four in binary, sixty-four in octal, and two hundred and fifty-six in hex — which is why prefixes like 0b, 0o, and 0x exist and why omitting them in documentation causes real confusion.

Conversion is instant in your browser.

Our Number Base Converter is completely free to use with no signup required. For this tool, processing runs in your browser — your files and data stay on your device and are not uploaded to our servers.

Whether you are a developer, designer, student, or business owner, this tool is designed to save you time and make your workflow more efficient. Bookmark this page to access it whenever you need it — it will always be free.