Binary / Hex / Decimal / Octal Converter
Convert between number bases instantly. Type in any field and all others update in real time.
Only 0 and 1 allowed
Only 0-9 allowed
Only 0-9 and A-F allowed
Only 0-7 allowed
Free Online Number Base Converter
This tool lets you convert numbers between binary (base 2), decimal (base 10), hexadecimal (base 16), and octal (base 8) systems instantly. All four fields are synchronized bidirectionally: type a value in any field and the others update in real time. It is perfect for developers, students, and anyone working with different number representations in programming, networking, or digital electronics.
How to Use
Enter a number in any of the four input fields. As you type, the corresponding values in all other number bases are calculated and displayed automatically. Only valid characters for each base are accepted: 0-1 for binary, 0-9 for decimal, 0-9 and A-F for hexadecimal, and 0-7 for octal. If you enter an invalid character, an error message will appear. Press the "Clear All" button to reset all fields.
FAQ
What is the binary number system?
Binary is a base-2 number system that uses only the digits 0 and 1. It is the fundamental language of computers, where each digit (bit) represents an on or off state. For example, the decimal number 10 is represented as 1010 in binary.
What is hexadecimal used for?
Hexadecimal (base 16) is widely used in computing as a compact way to represent binary data. Each hex digit maps to exactly four binary digits (bits), making it easy to read memory addresses, color codes (like #FF5733), MAC addresses, and other binary values in a shorter format.
What is the octal number system?
Octal is a base-8 number system using the digits 0 through 7. It was historically popular in computing because each octal digit represents exactly three binary digits. Today it is still used in Unix file permission notation (e.g., chmod 755) and some programming contexts.
How do I convert between number bases manually?
To convert from any base to decimal, multiply each digit by its base raised to the power of its position (starting from 0 on the right) and sum the results. To convert from decimal to another base, repeatedly divide by the target base and collect the remainders in reverse order. This tool automates both processes for you instantly.