Number Base Converter
Convert numbers between binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16).
Type in any field — all others update instantly.
Quick Reference Table
| Dec | Bin | Oct | Hex |
|---|
How to Use
Type your number into any field — decimal, binary, octal, or hex.
All other fields update automatically with the converted value.
Click Copy next to the field you need.
Frequently Asked Questions
What is binary (base 2)?
Binary is the number system used by computers. It uses only two digits: 0 and 1. Each digit is called a "bit". For example, the decimal number 10 is written as 1010 in binary.
What is hexadecimal (base 16)?
Hexadecimal uses 16 symbols: 0–9 and A–F. It is widely used in programming because one hex digit represents exactly 4 bits, making it a compact way to write binary numbers. Colors in CSS (like #FF5733) and memory addresses are typically written in hex.
What is octal (base 8)?
Octal uses digits 0–7. It was common in older computing systems and is still used in Unix file permissions (e.g., chmod 755). Each octal digit represents exactly 3 bits.
Why do programmers use hexadecimal?
Hexadecimal is more compact than binary and maps cleanly to binary (1 hex digit = 4 bits = 1 nibble). This makes it easy to read memory addresses, color codes, and byte values without the verbosity of raw binary.