Base Converter: Convert Numbers Between Binary, Octal, Decimal, and Hex

What Is Number Base Conversion?

A number base (or radix) defines how many unique digits a positional number system uses. Decimal uses 10 digits (0-9), binary uses 2 (0-1), octal uses 8 (0-7), and hexadecimal uses 16 (0-9 and A-F). The same integer value looks completely different written in each base.

For example, the decimal number 255 is FF in hexadecimal, 11111111 in binary, and 377 in octal. All four represent exactly the same value — only the notation differs.

Computers store data in binary. Hexadecimal is used as a compact shorthand because one hex digit represents exactly four binary bits (a nibble), making it easy to read binary patterns. Octal is less common today but still appears in Unix file permissions.

• Binary (base 2): used internally by all CPUs and digital hardware
• Octal (base 8): used for Unix chmod permissions (e.g., 755, 644)
• Decimal (base 10): the standard human number system
• Hexadecimal (base 16): used for memory addresses, color codes, and byte values

How to Use This Tool

Enter your number in any of the four input fields. All other fields update instantly. You can also use the copy button next to each field to copy the result.

1. 1

   Open the Base Converter

   Navigate to the Base Converter tool at DevTools.

2. 2

   Type your number

   Enter a number in any of the four fields: binary, octal, decimal, or hex.

3. 3

   See all conversions instantly

   The other three fields update in real time as you type.

4. 4

   Copy the result

   Click the copy icon next to any field to copy that representation to your clipboard.

5. 5

   Clear and try another

   Delete the input and type a new number to convert another value.

Common Use Cases

Base conversion comes up constantly in low-level programming, system administration, and computer science coursework.

• Debugging: reading hex memory addresses and converting to decimal for arithmetic
• Unix permissions: understanding chmod 755 means 111 101 101 in binary
• Color codes: converting CSS hex colors (#FF5733) to RGB decimal values
• Networking: working with IPv4 addresses and subnet masks in binary
• Embedded systems: writing register values and bitmasks in hex or binary
• Cryptography: working with hash outputs in hexadecimal

Tips and Best Practices

A few habits make base conversion faster and less error-prone.

• Group binary digits in sets of 4 (nibbles) for readability: 1111 0000 not 11110000
• Prefix hex with 0x in code (0xFF) and binary with 0b (0b11001100) for clarity
• Remember: 1 hex digit = 4 binary bits = half a byte (nibble)
• Two hex digits = 1 byte = 8 binary bits. Three octal digits = 1 byte
• When reading chmod output, split 9 binary bits into three groups of 3 (owner/group/other)

Frequently Asked Questions