UTF-8 Bytes and Encodings, Side by Side

Features

• Six representations at once: bytes, code points, percent-encoding, two kinds of HTML entity, and Unicode escapes
• Each row copies on its own — no hand-selecting a slice out of a long string
• Split by code point, so emoji are never cut into two orphaned surrogate halves
• Characters outside the BMP are written as surrogate pairs (\ud83d\ude00) that paste straight into config files
• Character count and byte count kept separate — the UTF-8 expansion at a glance
• Runs entirely in the browser; nothing is uploaded

How to use

1. Paste your text into the input box
2. Results appear as you type, one row per representation
3. Click a row's copy button to take just that value
4. Use Copy all when you want the whole block

FAQ

Why are the character and byte counts different?

Because UTF-8 is a variable-length encoding: ASCII characters (English letters, digits, punctuation) take 1 byte, Latin supplements and Greek take 2, CJK characters 3, and emoji or rare characters 4. So two CJK characters are 2 characters and 6 bytes, while "a" plus one CJK character plus one emoji is 3 characters and 8 bytes. A database `varchar(10)` counts characters and stores ten CJK characters fine — but a field measured or truncated in bytes holds only three. That row is where such problems come from.

How is this different from the URL encoder?

The percent-encoding row is the same thing, but the purpose differs. url-encode is a converter, with options for which characters to encode and whether spaces become + or %20, and its output is the answer. This is a comparison view, showing six forms of the same content at once. Use the focused tool to convert; use this to see what a string actually contains.

Why do emoji escapes come in two halves?

Because an emoji such as U+1F600 sits above the Basic Multilingual Plane, and a single UTF-16 code unit — what JavaScript and Java use — holds only 16 bits, not enough for it. It must therefore be written as a surrogate pair, \ud83d\ude00. The shorter \u{1F600} form exists, but Java properties files, older JSON parsers and many template engines reject it. This tool emits the surrogate pair, because pasting into a config file that works is the most common reason to be here.

Why two kinds of HTML entity?

The decimal form 中 and the hexadecimal form 中 denote the same character, and browsers accept both. It is purely convention: both appear in the wild, and some older editors or template engines accept only one. Listing both saves you a second conversion to satisfy a particular tool.