Number Base Converter
Convert numbers between binary, octal, decimal, hexadecimal and any base from 2 to 36 with our free online base converter.
How to Use This Calculator
- Enter a number in the input field.
- Select its source base (binary, octal, decimal, or hexadecimal).
- Click Convert to see the equivalent in all four bases simultaneously.
- Digits for bases above 10 use letters A–Z (A=10, B=11, ... Z=35).
- Toggle the conversion steps to see the detailed working.
Formula
To convert from base b to decimal, multiply each digit by b raised to the power of its position and sum the results. To convert decimal to base b, repeatedly divide by b and collect remainders.
Examples
IP Networking
192.168.1.1 in binary is 11000000.10101000.00000001.00000001 — essential for understanding subnet masks.
Color Codes
CSS uses hex like #FF5733 where FF=255, 57=87, 33=51 in decimal. Each pair represents one RGB channel.
File Permissions
Unix permissions use octal: chmod 755 means rwxr-xr-x. 7=111 (rwx), 5=101 (r-x) in binary.
Frequently Asked Questions
What is a number base?
A number base (or radix) determines how many unique digits are used. Base 10 (decimal) uses 0–9, base 2 (binary) uses 0–1, and base 16 (hex) uses 0–9 plus A–F.
Why is hexadecimal used in computing?
Hex represents 4 bits with a single digit, making binary data more compact and human-readable. One hex digit = exactly 4 binary digits.
What is the 0x prefix?
The prefix 0x (e.g., 0xFF) is a common convention in programming to indicate that a number is written in hexadecimal.
What bases can I convert between?
Any base from 2 to 36 is supported. For bases above 10, letters A through Z represent values 10 through 35.