Base Converter (Bin/Oct/Dec/Hex)

Convert any integer between binary (2), octal (8), decimal (10), and hexadecimal (16).

Result

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General calculation reads

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Steven Strogatz - accessible math

Scientific calculator (Casio fx-991EX)

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How to use this calculator

Enter value (with or without 0x/0b prefix).
Pick the base of the input.
Read all four common bases.

About this calculator

Number bases (radices) express the same integer with different digit symbols. Binary (base 2): only 0 and 1, foundation of digital computers. Hex (base 16): 0-9, A-F, used for memory addresses and color codes. Octal (base 8): rare today except Unix file permissions. Conversion is mechanical: parse from any base, output in any. JavaScript built-ins handle bases 2-36.

Frequently asked

Why hex?+

Each hex digit = 4 bits. 8-bit byte = 2 hex digits (00 to FF). Easier to read than long binary strings.

Color hex code?+

#RRGGBB — 3 hex bytes. #FF0000 = pure red, #00FF00 = green, #0000FF = blue, #FFFFFF = white.

Octal still used?+

Mostly Unix file permissions (chmod 755). Otherwise rare. C uses leading 0 for octal literals (0755).

Negative numbers?+

Use two's complement representation. JS Number's toString gives a minus sign instead. This calc covers integers ≥ 0.

Bigger than 32-bit?+

JS Number handles up to 2^53. For arbitrary-precision, use BigInt and BigInt.toString(base).

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