Convert between binary, decimal, hexadecimal, and octal — live as you type.
Humans count in base 10 (decimal) using digits 0-9. Computers operate in base 2 (binary) using only 0 and 1. Developers frequently work with base 16 (hexadecimal, digits 0-9 plus A-F) because each hex digit maps neatly to 4 binary bits, making it a compact way to represent binary data.
Octal (base 8) uses digits 0-7 and appears in Unix file permissions — 755 means owner can read/write/execute, while group and others can only read/execute. Hexadecimal is everywhere: CSS colors (#FF5733), memory addresses, MAC addresses, and byte-level debugging.
Converting between bases is straightforward mathematically but tedious by hand. This tool converts instantly between binary, decimal, hexadecimal, and octal, which is useful when debugging bitwise operations, reading hex dumps, setting file permissions, or working with color values.
This tool in other languages:
Français:
Convertisseur de base numérique
Español:
Convertidor de base numérica
Deutsch:
Zahlenbasis-Konverter
Português:
Conversor de base numérica
日本語:
基数変換ツール
中文:
进制转换工具
한국어:
진법 변환기
العربية:
محول الأنظمة العددية
Type a number in any of the four input boxes and all the others update in real-time. Type 255 in decimal and you'll see FF (hex), 11111111 (binary), and 377 (octal). No button clicks needed.
The tool uses JavaScript's native number handling with BigInt support, so very large numbers work fine. Preset buttons include common boundaries: 255 (8-bit), 65535 (16-bit), 16777215 (24-bit color), and MAX_INT32 (2147483647).
Hex is compact (one digit represents 4 bits) and maps cleanly to binary. A byte = two hex digits, a 32-bit value = 8 hex digits. Colors (#FF00AA), memory addresses (0x7fff8000), and character codes (U+2764) all use hex because it's dense and easy to read at a glance.
Split the 6-digit hex color into pairs: #FF0080 is FF, 00, 80. Paste each pair into the hex input to get decimal: 255, 0, 128 — that's your RGB value.
Mostly Unix file permissions (chmod 755 is octal). Each digit represents read/write/execute bits for owner, group, and world. For that specific use case, the Chmod Calculator has a visual checkbox interface.