Number Base Converter

Convert numbers between binary, octal, decimal, hexadecimal, and any base from 2 to 36. All fields update live as you type.

Common Bases

Binary (2)

Octal (8)

Decimal (10)

Hex (16)

Custom Base

Base (2-36)

Value

Features

Base 2-36 conversion

Real-time sync

Large number support

How to Use

1. Type a number into any of the base fields (binary, decimal, hex, etc.).

2. All other bases update automatically.

3. Click any value to copy it.

About this tool

Computers count in binary, programmers read memory addresses and colours in hexadecimal, Unix permissions use octal, and people think in decimal. This converter keeps all four in sync: type a value in any field and the others update immediately, with an extra field for any base from 2 to 36 using digits 0–9 and letters A–Z. It checks that every character is valid for the chosen base, so an 8 typed into the binary field is flagged instead of producing a wrong answer. Values are whole numbers up to JavaScript's safe integer limit of 9,007,199,254,740,991 (2^53 − 1). It is useful for bit flags, colour codes, file permissions, network masks and computer science homework.

Frequently Asked Questions

How do I convert binary to decimal by hand?

Multiply each digit by 2 raised to its position, counting from 0 on the right, and add the results. For 1011: 1×8 + 0×4 + 1×2 + 1×1 = 11.

Why is hexadecimal so common in programming?

Each hex digit represents exactly four bits, so a byte is always two hex digits (00 to FF). That makes hex a compact, readable way to write binary data, colours such as #FF8800 and memory addresses.

What is the largest number I can convert?

Up to 9,007,199,254,740,991, the largest integer JavaScript numbers represent exactly. Larger values would silently lose precision, so the tool shows an error instead.

Does it support negative numbers or fractions?

The converter works with non-negative whole numbers. Negative values in computing are usually stored as two's complement for a fixed bit width, and fractional parts need separate handling, so convert those with a programming language.

What are bases above 16 used for?

Base 32 and base 36 turn long numbers into short strings using letters and digits, which is handy for URL shorteners, compact IDs and case-insensitive codes.