Number Base Converter
Convert numbers between binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16). BigInt-safe for arbitrarily large numbers.
Decimalbase 10
Hexadecimalbase 16 · prefix 0x
Binarybase 2 · prefix 0b
Octalbase 8 · prefix 0o
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Bases in computing
- Binary (base 2) — two digits, 0 and 1. Native language of CPUs and memory. Useful for bitwise operations, flags, and low-level debugging.
- Octal (base 8) — eight digits, 0–7. Common in Unix file permissions (
chmod 755) because each digit maps to three binary bits. - Decimal (base 10) — everyday numbers.
- Hexadecimal (base 16) — digits 0–9 plus letters A–F. Compact binary notation — two hex digits = one byte. Used for colors (
#FF0080), memory addresses, hashes, and UUIDs.
How to use
- Type a number into any field — the other three update live.
- Prefixes
0x,0b,0oare accepted and optional. - Toggle Uppercase hex and Group digits for readable output.
- Click Copy next to any field.
Arbitrarily large numbers
The converter uses JavaScript BigInt, so you can paste numbers with hundreds of digits — cryptographic keys, SHA hashes, blockchain addresses — without precision loss. Standard 64-bit floats would silently round these, leading to wrong results.
Common use cases
- Converting HTTP status codes or color values between bases
- Reading hex dumps of binary files
- Debugging bitwise flags (
0b1010_0001→0xA1) - Inspecting Unix permissions (
0o755→rwxr-xr-x) - Examining large crypto values (SHA-256 outputs, RSA moduli)
Privacy
Everything is computed locally with native BigInt. Nothing is uploaded.