Convert numbers between binary, decimal, hexadecimal, and octal — instantly, free, no signup.
Type in any field — all others update instantly.
Type in any field — decimal, binary, hex, or octal. All other fields update instantly as you type.
All four representations appear simultaneously so you can compare number bases side by side.
Use the Text ↔ Binary section to convert ASCII text to its binary representation and back.
Type the decimal number in the Decimal field. The binary equivalent appears instantly in the Binary field. For example, 255 in decimal is 11111111 in binary.
Hexadecimal (base 16) is used in programming, memory addresses, color codes (#FF5733), and machine code because it compactly represents binary values — one hex digit = 4 binary bits.
Octal (base 8) is used in Unix/Linux file permissions (e.g. chmod 755) and some legacy computing systems. Each octal digit represents 3 binary bits.
It handles JavaScript's safe integer range: up to 2^53 − 1 (9,007,199,254,740,991 in decimal). For larger numbers, use specialized big integer libraries.