Number Base Converter — Binary, Hex, Decimal & Octal

Convert between binary, hex, decimal, octal and any base (2-36) instantly. Free, private — all processing in your browser.

No Tracking Runs in Browser Free

Input Number

Source Base

Prefixes 0x/0b/0o auto-detect base.

Binary (Base 2)

Octal (Base 8)

Decimal (Base 10)

Hexadecimal (Base 16)

Custom Base

Code Literals

Grouped Binary

Reviewed for mathematical accuracy and BigInt precision — Go Tools Engineering Team · Mar 22, 2026

Our engineering team verifies all base conversion logic against standard mathematical definitions and tests arbitrary-precision arithmetic for correctness.

What Is a Number Base Converter?

A number base converter is a tool that translates values between different positional numeral systems, each defined by its radix (as described in Knuth's *The Art of Computer Programming*, Vol. 2, "Seminumerical Algorithms") — the number of unique digits used. Every numeral system is positional, meaning a digit's value depends on its position within the number. The radix determines the multiplier for each position: in base 10, positions represent powers of 10; in base 16, powers of 16. A base converter automates the arithmetic of translating a value from one radix to another.

The four most common bases in computing are binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16). Binary is the native language of processors, representing data as sequences of 0s and 1s. Octal maps neatly to 3-bit groups and is used for Unix file permissions. Decimal is the human-readable default. Hexadecimal compresses 4 bits into a single character, making it the standard for memory addresses, CSS color codes, and byte-level data inspection. Other bases appear in specialized contexts — for instance, base 64 is used in data encoding (see our Base64 encoder for that use case).

Hexadecimal is the dominant representation format in modern computing. Memory debuggers display addresses in hex (e.g., 0x7FFF5FBFF8C0), CSS and graphic design tools express colors as hex triplets (e.g., #FF5733), network MAC addresses are written as six hex-separated octets, and binary file formats embed hex signatures called magic numbers that identify file types. The reason is straightforward: each hex digit maps exactly to 4 binary bits (a nibble), so a full byte is always two hex digits — compact, unambiguous, and easy to read.

This tool supports any integer base from 2 to 36, using digits 0-9 and letters A-Z for bases above 10. It is powered by JavaScript's BigInt, enabling arbitrary-precision arithmetic with no upper limit on digit count. For floating-point representations, the IEEE 754 standard defines how binary and hexadecimal formats map to the internal representation used by virtually all modern processors. All processing runs entirely in your browser — no data is transmitted to a server, ensuring complete privacy for sensitive values like cryptographic keys or proprietary identifiers.

Base conversion is also fundamental to understanding the output of cryptographic tools — for example, MD5 and SHA hash generators produce hexadecimal output, and UUID identifiers are formatted as 32 hex digits in the 8-4-4-4-12 pattern.

// Convert decimal 255 to other bases
console.log((255).toString(2));  // → '11111111'  (binary)
console.log((255).toString(8));  // → '377'       (octal)
console.log((255).toString(16)); // → 'ff'        (hexadecimal)

// Parse binary/hex strings back to decimal
console.log(parseInt('11111111', 2)); // → 255
console.log(parseInt('ff', 16));      // → 255

// JavaScript code literals (same value, different syntax)
const bin = 0b11111111; // 255  (binary literal)
const oct = 0o377;      // 255  (octal literal)
const hex = 0xff;       // 255  (hex literal)

Key Features of This Base Conversion Tool

Real-Time Multi-Base Conversion

See results in binary, octal, decimal, and hexadecimal simultaneously — all fields update instantly as you type.

Custom Base Support (2-36)

Convert to and from any base between 2 and 36 using digits 0-9 and letters A-Z.

Arbitrary Precision with BigInt

No size limit on input numbers. Convert values with hundreds of digits without precision loss.

Code-Ready Output

Copy values as programming language literals (0b, 0o, 0x) ready for JavaScript, Python, Go, Rust, and C.

Grouped Binary Display

Binary output is displayed with nibble grouping (4-bit groups) for easy visual inspection.

100% Browser-Based

All processing happens locally in your browser. No server uploads, no tracking, no cookies — your data never leaves your device.

Base Conversion Examples

Binary to Decimal — ASCII Character Code

The binary value 1000001 equals decimal 65, which is the ASCII code for the uppercase letter 'A'. Understanding this mapping is fundamental to text encoding in computing.

Decimal to Binary — Subnet Mask

11111111

Decimal 255 converts to binary 11111111 — a full octet of 1s. This is the building block of subnet masks like 255.255.255.0, where each octet is either all 1s or all 0s in classful networking.

Decimal to Hexadecimal — RGB Color Channel

FF

Decimal 255 is FF in hexadecimal, representing the maximum value for a single RGB color channel. CSS colors like #FF5733 use two hex digits per channel: FF (red), 57 (green), 33 (blue).

Hex Color to Binary

FF5733

1111 1111 0101 0111 0011 0011

Convert a CSS hex color code to its binary representation to understand individual bit patterns

Hexadecimal to Decimal — Memory Address

1A3F

The hex address 0x1A3F equals decimal 6719. Debuggers and memory inspectors display addresses in hexadecimal because it maps cleanly to binary, but decimal values are sometimes needed for pointer arithmetic and offset calculations.

Unix Permission to Decimal

Convert an octal Unix file permission (rwxr-xr-x) to its decimal equivalent

Binary IP Octet to Decimal

11000000

Convert a binary IP address octet to decimal — the first octet of 192.168.x.x

Large Number in Base 36

LFLS

Encode a large decimal number into a compact base-36 string, commonly used in URL shorteners

Common Base Conversions

Quick reference for the most frequently used number base conversions.

How to Convert Binary to Hexadecimal

Binary (Base 2) → Hexadecimal (Base 16)

Group binary digits into sets of 4 from right to left, then map each group to its hex equivalent. For example, 1010 1111 becomes AF. To convert hex back to binary, expand each hex digit to its 4-bit binary equivalent.

10101111 → AF

Each hex digit represents exactly 4 binary bits — memorize the 0-F mapping and conversions become instant.