Base

Number Base Converter

Convert between binary, octal, decimal, and hexadecimal online. Enter a value in any field to update the others with invalid format warnings.

Base inputs

Binary base 2 Ternary base 3 Quaternary base 4 Quinary base 5 Senary base 6 Septenary base 7 Octal base 8 Nonary base 9 Decimal base 10 Duodecimal base 12 Hexadecimal base 16 Base32 base 32 Base36 base 36

Conversion rules

Positional expansion

Any base-N number can be expanded by multiplying each digit by its power of N and summing the result.

101010₂ = 1×2⁵ + 0×2⁴ + 1×2³ + 0×2² + 1×2¹ + 0×2⁰ = 42₁₀

Decimal to another base

Repeatedly divide by the target base, record remainders, then read the remainders in reverse order.

42 ÷ 16 = 2 ... 10(A)
2 ÷ 16 = 0 ... 2
42₁₀ = 2A₁₆

Valid digits

Base N only allows digits smaller than N. Bases above 10 use A-Z for 10-35, so A is 10 in hexadecimal and Z is 35 in base36.

0b101010 = 0o52 = 42 = 0x2A

Common base conversion code

JavaScript

const value = BigInt("42");
const binary = value.toString(2);
const octal = value.toString(8);
const hex = value.toString(16).toUpperCase();

Python

value = int("2A", 16)
binary = bin(value)[2:]
octal = oct(value)[2:]
hex_value = hex(value)[2:].upper()

Java

long value = Long.parseLong("2A", 16);
String binary = Long.toString(value, 2);
String octal = Long.toString(value, 8);
String hex = Long.toString(value, 16).toUpperCase();

Go

value, _ := strconv.ParseInt("2A", 16, 64)
binary := strconv.FormatInt(value, 2)
octal := strconv.FormatInt(value, 8)
hex := strings.ToUpper(strconv.FormatInt(value, 16))

C#

var value = Convert.ToInt64("2A", 16);
var binary = Convert.ToString(value, 2);
var octal = Convert.ToString(value, 8);
var hex = Convert.ToString(value, 16).ToUpperInvariant();

PHP

$value = intval("2A", 16);
$binary = base_convert((string)$value, 10, 2);
$octal = base_convert((string)$value, 10, 8);
$hex = strtoupper(base_convert((string)$value, 10, 16));