What is the difference between UTF-16 LE and BE?

Both encode the same 16-bit code units, but little-endian stores the low byte first and big-endian stores the high byte first. For example U+0041 (A) is 41 00 in LE and 00 41 in BE. Windows and most x86 software default to LE.

How are emoji and rare characters encoded?

Characters above U+FFFF cannot fit in one 16-bit code unit, so UTF-16 splits them into a surrogate pair: a high surrogate in D800-DBFF followed by a low surrogate in DC00-DFFF. Each surrogate becomes two hex bytes, so such characters take four bytes.

Does this add a byte order mark (BOM)?

No. The viewer shows only the encoded text bytes. A real UTF-16 file often starts with FF FE (LE) or FE FF (BE) as a BOM, but that is metadata you would prepend separately.

Why does my character count differ from the byte count?

Each basic character is two bytes, but astral characters such as emoji use four bytes because of surrogate pairs. So byte count is at least twice the code-unit count and can be higher than twice the visible character count.

Is the conversion lossless?

Yes. UTF-16 can represent every Unicode code point, so the hex output round-trips back to the original string exactly, regardless of language or symbol.

UTF-16 Hex Viewer — Gera Tools

UTF-16 stores text as 16-bit code units. This viewer turns any string into its raw UTF-16 byte stream in hexadecimal, in either little-endian or big-endian order, so you can see precisely how the text would sit in memory or in a file.

How it works

JavaScript strings are already UTF-16 internally, so each charCodeAt index returns one 16-bit code unit (0 to 65535). For each code unit the tool splits it into a high byte and a low byte:

high = (unit >> 8) & 0xFF
low  =  unit       & 0xFF
LE   = low  high      (low byte first)
BE   = high low       (high byte first)

Characters above U+FFFF are already represented in the string as a surrogate pair of two code units, so they naturally expand to four bytes without any extra handling. Each byte is printed as two zero-padded hex digits.

Example and notes

The text Hi is two code units, 0048 0069. In little-endian that is 48 00 69 00; in big-endian it is 00 48 00 69. An emoji such as a rocket is a single character but two code units (a surrogate pair) and therefore four bytes. If you need the bytes for a file, remember a UTF-16 file usually leads with a BOM (FF FE for LE) which this tool deliberately omits so you see only the text.