Why is hexadecimal used so much in computing?

Because each hexadecimal digit is exactly four bits, so a byte is always two digits and converting to binary needs no arithmetic. It is a compact way of writing binary that people can actually read.

Why are file permissions written in octal?

Because each octal digit is exactly three bits, matching the read, write and execute triple. 755 is 111 101 101, which is the permission set written directly.

What is the highest base supported?

Base 36, which uses the digits 0 to 9 followed by A to Z. Beyond that there are no conventional characters, though base 62 and base 64 exist with their own defined alphabets.

Does converting change the number?

No. Fifteen, F and 1111 are the same quantity written in decimal, hexadecimal and binary. Only the notation changes, the way a number does when you say it in another language.

Number Base Converter

Binary, octal, decimal, hex — and any base from 2 to 36.

Everything runs inside your browser. Your files never leave your device.

Input

Result

The result appears here as you type.

Ask about Number Base Converter

Questions about what this tool does, which option to pick, or what it can and cannot handle.

The question you type here is sent to an AI provider to be answered — your files and whatever you put in the tool above are not, and the assistant cannot see them. Answers are generated and can be wrong. The tool itself is not guessing: it runs deterministic code on your device.

About the Number Base Converter

Numbers are written in a base, and the same quantity looks entirely different depending on which one. This converts between binary, octal, decimal, hexadecimal and any base from 2 to 36.

Hexadecimal exists because it maps cleanly onto binary: each hexadecimal digit is exactly four bits, so a byte is always two digits and the conversion is mechanical rather than arithmetic. That is why colours, memory addresses, hashes and byte dumps are all written in hex — it is binary that a person can read.

Binary is where the structure is visible. Bit flags, permissions and masks all make sense in binary and none of them makes sense in decimal. Unix file permissions are the everyday example: 755 in octal is 111 101 101 in binary, which is read-write-execute for the owner and read-execute for everyone else. Each octal digit is exactly three bits, which is precisely why permissions are written in octal in the first place.

Bases above 16 use letters beyond F, running to Z at base 36. Base 36 is occasionally used for short identifiers, since it packs the most information into the alphanumeric characters that are safe everywhere.

Digit grouping makes long binary readable, and the tool applies it to every line rather than only some. Grouping in fours aligns with hexadecimal digits; grouping in eights shows byte boundaries.

One thing a base conversion does not change is the number. Fifteen in decimal, F in hexadecimal and 1111 in binary are the same quantity written three ways, in the same sense that "fifteen" and "quinze" are the same number in two languages.

How to use it

1Enter the number and say which base it is currently in.
2Read the conversions into the other common bases.
3Set a custom base for anything outside binary, octal, decimal and hexadecimal.
4Switch on digit grouping to make long binary readable — fours for hex alignment, eights for byte boundaries.

Questions

Why is hexadecimal used so much in computing?: Because each hexadecimal digit is exactly four bits, so a byte is always two digits and converting to binary needs no arithmetic. It is a compact way of writing binary that people can actually read.
Why are file permissions written in octal?: Because each octal digit is exactly three bits, matching the read, write and execute triple. 755 is 111 101 101, which is the permission set written directly.
What is the highest base supported?: Base 36, which uses the digits 0 to 9 followed by A to Z. Beyond that there are no conventional characters, though base 62 and base 64 exist with their own defined alphabets.
Does converting change the number?: No. Fifteen, F and 1111 are the same quantity written in decimal, hexadecimal and binary. Only the notation changes, the way a number does when you say it in another language.