# Number Base Converter

> Convert between binary, octal, decimal, and hexadecimal. Type in any field and the other three update live.

URL: https://uttir.com/number-base-converter
Categories: developer-tools
Privacy: Math runs locally. No data leaves your browser.

## About

Computers represent numbers in different bases. Decimal (base 10) is what humans use. Binary (base 2) is what computers actually use internally. Octal (base 8) and hexadecimal (base 16) are compact ways to write binary, used in file permissions, color codes, memory addresses, and more.

Type a value in any of the four fields and the other three update live. Handles arbitrary-precision integers up to 2^53 cleanly; for very large numbers, use the BigInt-safe API.

## How to use

1. **Type a value** — In any of the four base fields — binary, octal, decimal, or hex.
2. **Read the conversions** — The other three fields update live.
3. **Copy** — Select and copy whatever form you need.

## Examples

### A typical byte

255 in every base.

Output:

```
Bin 11111111 · Oct 377 · Dec 255 · Hex FF
```

### IPv4 octet

192.168.0.1 — each octet in decimal, binary, hex.

Output:

```
192 → 11000000 → C0 · 168 → 10101000 → A8
```

## FAQ

### Why does hex use letters A-F?

Because hex needs 16 symbols and we only have 10 digits (0-9). The letters A-F stand in for the values 10-15. So "FF" in hex = 15*16 + 15 = 255 in decimal.

### What is the largest number this handles?

The converter uses BigInt internally, so it handles numbers of any practical size — well beyond 2^53. Display formatting also uses BigInt so the result is always exact.

### What is hexadecimal used for?

Color codes (#FF0000), memory addresses, low-level programming, and any place where binary is too long. Each hex digit is exactly 4 binary digits, which makes it a compact way to write binary.

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