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Number Base Converter

Convert between binary, octal, decimal, hexadecimal and any base from 2 to 36; e.g. 255 = FF.

Runs in your browser Free

Type in any field; the others update instantly. Very large whole numbers are supported.

Convert between number systems

Computers work in binary (base 2), programmers use hexadecimal (base 16) for colours, memory addresses and bytes, and octal (base 8) for Unix file permissions. The Number Base Converter switches between them instantly.

How it works

Type a number in any field and every other base updates. For example, decimal 255 = binary 11111111 = hex FF = octal 377. Besides the common bases you can use any base from 2 to 36.

Exact for big numbers

The tool uses BigInt, so even very long binary or hexadecimal values convert without losing precision. Ideal for computer science students, embedded developers and network engineers.

How to use Number Base Converter

  1. Type the number into the field for its base.
  2. The other bases are calculated instantly.
  3. Choose a custom base (2–36) if needed.
  4. Copy the result you need.

Why use this tool?

Shows every base on one screen without switching calculator modes, with exact results for big numbers.

FAQ

Can I convert negative or fractional numbers?

Negative integers are supported with a minus sign. Fractions can't be represented exactly in most bases, so they aren't converted.

What do A–F mean in hexadecimal?

They represent 10 to 15: A = 10, B = 11, … F = 15.

What does Linux permission 755 mean?

Octal 755 is binary 111 101 101: read-write-execute for the owner and read-execute for everyone else.

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