Base Converter FREE | Binary Decimal Hex Octal Converter Online

Base Converter FREE | Binary, Decimal, Hex and Octal

Convert numbers between binary (base 2), octal (base 8), decimal (base 10), hexadecimal (base 16), or any base from 2 to 36 instantly. All four standard bases are shown simultaneously. Click any result to copy it. Runs entirely in your browser.

Binary Base 2

Decimal Base 10

Hex Base 16

Any Base 2-36

Number Base Converter

Enter Number (type or paste)

Result

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Enter a number above to convert

All Standard Bases — click to copy

Binary (2) —

Octal (8) —

Decimal (10) —

Hex (16) —

Hexadecimal Alphabet

0 = 01 = 12 = 23 = 3 4 = 45 = 56 = 67 = 7 8 = 89 = 9A = 10B = 11 C = 12D = 13E = 14F = 15

Frequently Asked Questions

Binary (base 2) uses only 0 and 1. Each position represents a power of 2 starting from 2^0 = 1 on the right. To convert 1011 binary to decimal: (1 x 8) + (0 x 4) + (1 x 2) + (1 x 1) = 11. This tool uses JavaScript's built-in parseInt(value, fromBase) to parse the input into a decimal integer, then number.toString(toBase) to convert to any target base. This is accurate for integers up to 2^53 (approximately 9 quadrillion).

Hexadecimal (base 16) represents binary data compactly. Each hex digit maps to exactly four binary bits. Hex is used for web colour codes (#FF6600), memory addresses, cryptographic hash values (SHA-256 outputs a 64-character hex string), MAC addresses, escape sequences in strings, and machine code in debuggers. It is far more compact than binary while still mapping cleanly to binary boundaries.

The tool supports any base from 2 (binary) to 36. Bases 2-36 use digits 0-9 then letters A-Z for values 10-35. Quick preset buttons cover binary (2), octal (8), decimal (10), and hexadecimal (16). The Custom option lets you specify any from-base and to-base between 2 and 36. All four standard bases are always shown simultaneously in the results panel on the right.

Octal (base 8) uses digits 0-7. It was common in early computing because 6-bit and 12-bit architectures mapped neatly to groups of three bits. Today octal is mainly used in Unix and Linux file permission codes. For example chmod 755 encodes read/write/execute permissions as three octal digits, where each digit represents three binary bits for owner, group, and others respectively.

The error appears when your input contains digits that are not valid for the selected base. Binary only accepts 0 and 1. Octal accepts 0-7. Decimal accepts 0-9. Hexadecimal accepts 0-9 and A-F. If you select Binary and type a 2 or higher, the tool shows an error. Make sure to select the correct from-base that matches your input number before converting. Hex input is automatically converted to uppercase for you.

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Free Number Base Converter — Binary, Decimal, Hexadecimal, Octal and Custom Bases

Number base conversion is fundamental to computer science, electronics, and programming. Every piece of digital data exists as binary at the hardware level, and developers regularly work with hexadecimal for memory addresses, colour codes, and cryptographic hashes. The Base Converter on OneDocPDF converts numbers between any two bases from 2 to 36 instantly using JavaScript's parseInt and toString functions with radix support. All four common bases (binary, octal, decimal, hex) are always shown simultaneously for every input value, making it ideal for students and developers who need to cross-reference representations quickly.

Binary, octal, hexadecimal, and decimal are used throughout software development, cybersecurity, embedded systems programming, and digital circuit design. Web designers use hexadecimal for CSS colour codes. Network engineers use binary and hex for subnet masks and IP address calculations. Assembly programmers use hexadecimal for memory address notation. Mathematicians use various bases to demonstrate divisibility properties. This tool provides immediate conversion across all standard bases for any integer value.

For related tools, see our Color Code Converter which converts hex colour codes to RGB and HSL, our Scientific Calculator for advanced arithmetic, and our Hash Generator which produces hexadecimal hash outputs. All tools are completely free and run entirely in your browser.