Number Base Converter — Binary, Hex, Decimal & Octal

Convert any number between binary (base 2), decimal (base 10), hexadecimal (base 16), and octal (base 8) with a single input. This free number base converter is built for programmers, students, and anyone working with low-level data, memory addresses, or color values.

Why use this Number Base Converter?

Simultaneous conversion between binary, decimal, hex, and octal
Results update live as you type in any base
Handles large integers accurately without rounding errors
Free to use, no login, works offline in any modern browser

How to use the Number Base Converter

Select the input base: Choose whether your number is in binary, decimal, hexadecimal, or octal.
Enter your number: Type the number into the input field — only valid digits for the chosen base are accepted.
See all conversions at once: The equivalent values in all other bases appear instantly below the input.
Copy any result: Click the copy icon next to any base to copy that value for use in your code or notes.

Frequently Asked Questions

How do I convert binary to decimal?

Each binary digit represents a power of 2, starting from the rightmost digit (2⁰). To convert 1011 binary: (1×8) + (0×4) + (1×2) + (1×1) = 11 decimal. This converter does that math instantly for any size number.

Why do programmers use hexadecimal?

Hexadecimal is compact — one hex digit represents exactly 4 binary bits, so a full byte (8 bits) becomes just two hex characters. This makes hex ideal for representing memory addresses, RGB color values, and binary data in a human-readable format.

What is octal and when is it used?

Octal (base 8) uses digits 0–7. It was historically used in early computing and is still common in Unix file permissions (e.g. chmod 755), where each digit represents a group of three binary bits for read, write, and execute permissions.

Can this convert negative numbers?

The converter handles positive integers in standard base notation. For signed negative numbers in computing (two's complement), you'd need to know the bit width — that's a more specialized operation beyond standard base conversion.

How do I convert a hex color code to RGB?

Hex color codes like #FF5733 split into three 2-digit hex pairs: FF, 57, 33. Convert each pair from hex to decimal: 255, 87, 51. That gives you RGB(255, 87, 51). You can also use the Color Converter tool on AllTools for this directly.