Number Base Converter

Convert binary, octal, decimal and hex

Enter a value in any base and instantly see it in binary, octal, decimal and hexadecimal. The converter uses arbitrary-precision arithmetic (BigInt), so it handles values far beyond a 64-bit integer without losing digits — useful for hashes, bitmasks and large identifiers. Everything runs locally in your browser.

The four common bases

• Binary (base 2) — just 0 and 1; how computers store everything at the lowest level.
• Octal (base 8) — digits 0–7; still seen in Unix file permissions (e.g. chmod 755).
• Decimal (base 10) — the everyday human base.
• Hexadecimal (base 16) — digits 0–9 and a–f; compact and maps neatly to bytes, so it's everywhere in programming: colors, memory addresses, MAC addresses and hashes.

Why hex and binary go together

One hex digit represents exactly four bits (a "nibble"), and two hex digits make one byte. That clean mapping is why hexadecimal is the preferred shorthand for binary data — 0xFF is far easier to read than 11111111. When you're working with byte-level data, converting between hex and binary is a constant need.

Common uses

• Reading a hex color or memory address as decimal, or vice versa.
• Working out Unix permission bits in octal.
• Inspecting bitmasks and flags in binary.
• Converting a large hex hash or ID to decimal.

Tips

You can paste values with a 0x, 0b or 0o prefix — the converter strips it automatically. If you're converting bytes to readable characters instead of numbers, use the hex ↔ text converter; for Base64, see the Base64 tool.