Number Base Converter: Binary, Hex, Decimal (Free)

Computers think in binary, programmers read in hexadecimal, and humans count in decimal — and sooner or later you need to translate between them. Whether you are decoding a color code, reading a memory address or studying for a CS exam, a base converter saves you from error-prone hand math. This guide shows you how to convert number bases for free with the Number Base Converter, which handles binary, octal, decimal and hex, even for very large numbers, right in your browser.

What number bases are and how they work

A number base is simply how many distinct digits a counting system uses before it rolls over to the next place value.

• Binary (base 2) uses two digits, 0 and 1. Each place is a power of 2.
• Octal (base 8) uses 0 to 7. Each place is a power of 8.
• Decimal (base 10) uses 0 to 9 — the everyday system.
• Hexadecimal (base 16) uses 0 to 9 then A to F, where A is 10 and F is 15. Each place is a power of 16.

The value 255 in decimal is 11111111 in binary and FF in hex. The number itself does not change; only the way you write it does. Converting means re-expressing the same quantity in a different set of digits.

How to use the Number Base Converter

The tool converts in every direction at once:

1. Open the Number Base Converter.
2. Type a value into the field for the base you already have — for example paste a binary string into the binary box.
3. The other fields update instantly to show the same number in decimal, octal and hexadecimal.
4. Copy whichever result you need with a click.

There is no convert button to press and no waiting; results appear as you type.

Example conversions

Here is the same set of values shown across all four bases:

Notice how hex stays short while binary grows long — that is exactly why programmers prefer hex for writing out byte values.

Common use cases

Base conversion shows up across programming and electronics:

• Reading hex color codes and matching them to RGB values.
• Working with memory addresses, file permissions and bitmasks.
• Decoding hardware registers and network data in hex.
• Learning how computers store numbers in computer science courses.
• Setting Unix file permissions, which use octal notation.

If you are working with colors specifically, pair this with the Color Converter to turn a hex value straight into RGB or HSL.

Tips and common mistakes

A few things trip people up:

• Hex letters are not case sensitive; FF and ff mean the same value, but pick one style for consistency.
• Do not confuse the prefix conventions you see in code (0x for hex, 0b for binary) with the raw digits — enter just the digits here.
• Binary strings get long fast, so double-check you have the right count of 0s and 1s.
• This tool handles arbitrary-precision integers, so very large numbers convert exactly without the rounding errors a calculator might introduce.

Is it private and free

Yes. Every conversion runs locally in your browser using JavaScript big-integer math, so nothing you type is sent to a server. That keeps your data private and makes results appear instantly.

The converter is free with no sign-up and no limits. For more developer utilities, browse the developer tools category or the full all tools list. You might also like the hex and color tools for design work.