Free Number Base Converter - Binary, Hex, Octal, Decimal
Convert numbers between binary, octal, decimal and hexadecimal with live conversion and reference table.
What Is Number Base Converter?
A number base converter translates numbers between different numeral systems. The most common bases are decimal (base 10 — what we use daily), binary (base 2 — how computers think), octal (base 8 — used in Unix permissions) and hexadecimal (base 16 — used in colours, memory addresses and low-level programming). Each base uses a different set of digits to represent values.
Understanding number bases is fundamental to computer science and programming. Binary underpins all digital computation. Hexadecimal provides a compact way to represent binary data (every hex digit maps to exactly 4 binary digits). Octal appears in file permissions and some legacy systems.
How to Use This Tool
Enter a number in any supported base.
Select the input base (binary, octal, decimal, hexadecimal or custom).
View the number automatically converted to all other bases.
Copy any specific conversion using the copy button.
Tips & Best Practices
Each hexadecimal digit corresponds to exactly 4 binary digits — this is why hex is used as shorthand for binary.
Octal digits correspond to exactly 3 binary digits — Unix file permissions (chmod 755) use this relationship.
The maximum value of an 8-bit byte (11111111 in binary) is 255 in decimal or FF in hex.
Prefix conventions: 0b for binary (0b1010), 0x for hex (0xFF), 0o for octal (0o17).
Common Use Cases
Converting between hex colours (#FF0000) and their RGB decimal values (255, 0, 0).
Understanding and setting Unix file permissions using octal notation.
Debugging binary data by converting to hexadecimal for readability.
Learning computer science fundamentals — how computers represent numbers.