Number Base Converter

Convert between binary, octal, decimal, hexadecimal, and any base from 2 to 36. View binary bit patterns, ASCII mappings, and two's complement. All calculations happen locally — nothing leaves your browser.

Decimal Value

255

0xFF · 11111111 · 377

Binary

11111111

Octal

377

Hexadecimal

ASCII

Input Number

Number

Input Base

Binary Bit Display

Two's Complement (8-bit)

11111111

All Bases

ASCII Character Mapping

How to Use the Base Converter

Enter a number — type in any numeric value.
Select the input base — tell the calculator what base your number is in.
See all conversions — instantly view the number in every base.
View binary details — see individual bits, two's complement, and ASCII mapping.

Understanding Number Bases

A base (or radix) is the number of unique digits used to represent values. Base 10 (decimal) uses 0-9, Base 2 (binary) uses 0-1, Base 16 (hex) uses 0-9 and A-F. Each position in a number represents a power of the base.

Example: Hexadecimal FF = 15×16¹ + 15×16⁰ = 240 + 15 = 255 decimal = 11111111 binary.

Frequently Asked Questions

Two's complement is the standard way to represent negative integers in binary. To get the two's complement of a number: invert all bits (change 0s to 1s and vice versa), then add 1. For 8-bit, 255 (11111111) is also -1 in two's complement.

Hex is a compact representation of binary. Each hex digit maps to exactly 4 bits, making it easy to read binary values. Memory addresses, color codes (#FF5733), and byte values are commonly displayed in hex.

Each binary digit represents a power of 2, starting from the rightmost bit (2^0). Multiply each bit by its power of 2 and sum all values. For example, 1101 in binary = 1×8 + 1×4 + 0×2 + 1×1 = 13 in decimal. This tool does the conversion instantly for any base between 2 and 36.

Use Cases

Binary to Decimal

Convert binary numbers to decimal for computer science homework, digital logic design, and understanding computer architecture.

Hex Color Codes

Convert hex color codes like #FF5733 to decimal RGB values for CSS, design tools, and color manipulation tasks.

Legacy System Octal

Convert octal values to decimal when working with legacy Unix file permissions, older systems, and octal-based configurations.

IP Address Subnet Math

Perform subnet calculations for network configuration, understanding IP address ranges, and CIDR notation conversions.

Assembly Programming

Convert between number bases when working with assembly language, low-level programming, and memory address calculations.