Integer Base Converter

A number can be written in many bases. Humans use base 10, computers work in base 2, and programmers read memory addresses, colours and permissions in base 16 (hexadecimal) or base 8 (octal). This converter shows an integer in all common bases at once, so you can move between them without mental arithmetic.

How to use it

1. Enter a number and choose the base it is written in.
2. Read the value in binary, octal, decimal, hexadecimal and other bases.
3. Copy the representation you need.

Example: 255

• Binary (base 2): 11111111
• Octal (base 8): 377
• Decimal (base 10): 255
• Hexadecimal (base 16): FF
• Base 36: 73

How base conversion works

To convert from decimal, divide repeatedly by the target base and read the remainders from last to first. 255 ÷ 16 = 15 remainder 15, and 15 ÷ 16 = 0 remainder 15, giving F F. To convert back, multiply each digit by the base raised to its position: F × 16 + F = 15 × 16 + 15 = 255.

Shortcuts between binary, octal and hex

Each hex digit is exactly 4 bits and each octal digit is exactly 3 bits, so you can convert by grouping. 1101 0110 in binary is D6 in hex. That is why hex is the standard way to display bytes.

Prefixes in code

• 0x for hex, 0b for binary and 0o for octal in JavaScript, Python, Rust and many other languages.
• In C and older JavaScript, a leading zero alone means octal, so 010 is 8. Avoid leading zeros for decimal numbers.
• JavaScript numbers are exact only up to 2^53; use BigInt for larger values.