Number Base Converter Online Free — Binary, Octal, Decimal, Hex

Free online number base converter. Convert between decimal, binary, octal, and hexadecimal instantly. Supports integers and fractions with step-by-step conversion.

Type a number in any field and the other bases will be calculated automatically.

Decimal (Base 10)

Binary (Base 2)

Octal (Base 8)

Hexadecimal (Base 16)

About Number Base Systems

Different number base systems are used in computing: Binary (base 2) for machine-level operations, Octal (base 8) for Unix permissions, Decimal (base 10) for everyday use, and Hexadecimal (base 16) for memory addresses, colors, and compact binary representation.

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How to Use

Enter a number in any base (binary, octal, decimal, or hex)
All other base conversions update automatically
Copy any converted value with the copy button

Common Use Cases

Converting between hex and binary for programming
Working with RGB color codes
Understanding IP addresses and subnet masks
Debugging low-level data formats

Frequently Asked Questions

What are number bases?

Number bases (or radixes) are systems for representing numbers. Common bases: binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16).

Why do programmers use hexadecimal?

Hexadecimal is compact and maps neatly to binary — each hex digit represents exactly 4 binary bits. It's widely used for colors, memory addresses, and byte values.

What's binary used for?

Binary (base 2) is the fundamental language of computers. Understanding binary helps with bitwise operations, networking (IP addresses), and low-level programming.