Number Base Converter

Convert numbers between binary, octal, decimal and hexadecimal, including very large integers. Free online base converter.

About this tool

Convert integers between binary, octal, decimal and hexadecimal. Arbitrarily large numbers are handled exactly with BigInt.

Choose the base of your input.
Type the number; 0x, 0o and 0b prefixes, signs, spaces and underscores are accepted.
Copy the value in the base you need.

No. Only integers are supported.

With a minus sign, for example -a in hex. Two's complement is not used.

No practical limit; very long numbers are converted without rounding.

Base64 Encode / Decode – Convert text to and from Base64 (UTF-8)
URL Encode / Decode – Percent-encode or decode URL components
HTML Entity Encode / Decode – Escape and unescape HTML entities
Base64 Image Encode / Decode – Turn images into data URIs and preview Base64 images
Backslash Escape / Unescape – Escape quotes, newlines and control characters
Hex ↔ ASCII – Convert text to hexadecimal bytes and back
JWT Debugger – Decode JSON Web Token header and payload

UUID / ULID Generate / Decode – Generate UUID v4 / v7 and ULID, and decode existing IDs
Hash Generator – MD5, SHA-1, SHA-256, SHA-384 and SHA-512 digests
Random String Generator – Cryptographically secure random strings
Lorem Ipsum Generator – Placeholder text in paragraphs, sentences or words
QR Code Generate / Read – Create QR codes and read them from images

World Time Converter – Convert a time between time zones; starts from this computer's current time
Unix Time Converter – Convert Unix timestamps and date strings
Number Base Converter – Convert between binary, octal, decimal and hex
YAML ↔ JSON – Convert YAML to JSON and back
CSV ↔ JSON – Convert CSV to JSON and back
HTML to JSX – Convert HTML markup into React JSX
Query String ↔ JSON – Convert URL query strings to JSON and back
URL Parser – Split a URL into its parts and query parameters
Color Converter – Convert between HEX, RGB, HSL, HWB and CMYK
SVG to CSS – Turn SVG markup into a CSS background data URI
JSON ↔ PHP Array – Convert JSON to PHP array syntax and back
PHP Serialize / Unserialize – Convert JSON to PHP serialize() format and back