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Number Base Converter

Convert between binary, octal, decimal, and hexadecimal.

Binary
0b11111111
Octal
0o377
Decimal
255
Hexadecimal
0xFF

About This Tool

Free number base converter online — convert numbers between binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16) instantly. Type in any base and all other representations update live. Computer science students use this tool to understand how numbers are represented in different bases, to convert memory addresses from hex to decimal, to work through assembly language problems, and to verify manual conversions. Programmers use it when reading hex color codes (like #FF5733 = RGB 255, 87, 51), interpreting binary file headers, working with bitwise operations, and understanding IP address subnet masks.

How to Use

  1. 1

    Enter a number

    Type a value in any of the four fields: Binary, Octal, Decimal, or Hexadecimal.

  2. 2

    See all conversions

    All four representations update instantly as you type.

  3. 3

    Copy your result

    Click the copy icon next to the format you need.

Frequently Asked Questions

What is binary?+
Binary (base 2) uses only two digits: 0 and 1. Every number in a computer is ultimately represented in binary. For example, decimal 10 = binary 1010.
Why do programmers use hexadecimal?+
Hex (base 16) is compact — one hex digit represents exactly 4 binary bits. A byte (8 bits) is just two hex digits (e.g., 0xFF = 255). This makes hex easier to read than long binary strings.
What is decimal 255 in binary and hex?+
Decimal 255 = Binary 11111111 = Hex FF. Enter 255 in the Decimal field to verify.

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