Number Base Converter

Convert between decimal, binary, hexadecimal and octal instantly

Quick References
255 (0xFF) 256 (0x100) 65535 (0xFFFF) 10 (0b1010) 16 (0x10) 1024 (0x400)
How to Use the Number Base Converter
1
Type a number in any of the four fields — Decimal, Binary, Hex, or Octal
2
All other fields update automatically as you type
3
See the binary bit visualization for values up to 32 bits
4
Use the Copy buttons to copy any converted value
About Number Base Systems

Decimal (Base 10) — the everyday number system using digits 0–9. Binary (Base 2) — used internally by all computers, using only 0 and 1. Hexadecimal (Base 16) — uses 0–9 and A–F, widely used in programming for memory addresses, color codes, and byte values. Octal (Base 8) — uses digits 0–7, historically used in Unix file permissions (e.g. chmod 755).

Frequently Asked Questions
255 in binary is 11111111 — eight 1s. This represents the maximum value of a single byte (8 bits). In hexadecimal, 255 is FF. This is why #FFFFFF is white in CSS (255 red, 255 green, 255 blue).
Multiply each binary digit by 2 raised to its position power (from right, starting at 0) and sum the results. For example: 1010 = 1×8 + 0×4 + 1×2 + 0×1 = 10 in decimal.
Hexadecimal is used in programming for memory addresses, color codes (like #FF5733), byte values, and machine code. Each hex digit represents exactly 4 binary bits, making it a compact way to represent binary data.