Number Base Converter
Convert between Binary, Octal, Decimal, and Hexadecimal.
Binary (Base 2)
Octal (Base 8)
Decimal (Base 10)
Hexadecimal (Base 16)
Click any value to copy.
How to Convert Number Bases
- Enter a number — type any number in the Number input box (e.g. 255 for decimal, FF for hex, 11111111 for binary).
- Select the source base — choose Binary (2), Octal (8), Decimal (10), or Hexadecimal (16) from the "From base" dropdown.
- See all conversions — binary, octal, decimal, and hex results all appear simultaneously.
- Click to copy — click any result box to copy that value to your clipboard.
Frequently Asked Questions
How do I convert decimal to binary? ▼
Enter the decimal number in the input box and set "From base" to Decimal (10). The binary result appears in the Binary box instantly. For example: 255 decimal = 11111111 binary = FF hex = 377 octal.
How do I convert hexadecimal to decimal? ▼
Enter the hex number (e.g. FF or 1A3F) and set "From base" to Hexadecimal (16). The decimal equivalent appears immediately. FF = 255, 1A3F = 6719.
What is hexadecimal used for? ▼
Hexadecimal (base 16) is used extensively in computing: HTML/CSS color codes (#FF5733), memory addresses, byte values in debugging, file format headers (magic numbers), and machine code. One hex digit represents exactly 4 binary bits, making it a compact binary representation.
What is binary used for in computers? ▼
Binary (base 2) is the fundamental language of all digital computers. All data — text, images, programs — is ultimately stored and processed as binary. Understanding binary is essential for low-level programming, digital electronics, and computer architecture.
How do Unix file permissions use octal? ▼
Unix file permissions use octal (base 8). For example, chmod 755: owner has 7 (rwx = 111 binary), group has 5 (r-x = 101 binary), others have 5. Each octal digit represents three permission bits (read=4, write=2, execute=1).