UTF-16 to Hex Converter
Encode text as UTF-16 bytes in hex (big-endian, 2 bytes per code unit) — the format JavaScript strings use internally.
Built by
Swapnil SanghviFull-Stack Web Developer & WordPress Developer
Swapnil Sanghvi is a full-stack web and WordPress developer, UI designer, and full-time freelancer who builds and maintains Hex Calculator.
Further reading: Character encoding — Wikipedia
How to Convert Text to UTF-16 Hex
Every character becomes one 16-bit code unit (2 bytes) — or, for characters above U+FFFF like most emoji, a pair of code units (4 bytes total). Each unit is written as 4 hex digits, most significant byte first, concatenated in order.
Where UTF-16 Hex Actually Comes Up
Debugging a JavaScript String's Internals
JavaScript strings are UTF-16 under the hood — seeing the raw hex helps explain surprising behavior like .length counting an emoji as 2, or .charCodeAt() returning half of a surrogate pair.
😀 -> D83D DE00
Reading Windows API String Data
Windows APIs that take wide strings (WCHAR, LPWSTR) use UTF-16 natively — converting a known string to hex gives you the exact bytes to expect when inspecting memory or a captured buffer.
Hi! -> 0048 0069 0021
Comparing Java char Array Contents
Java's char type is a 16-bit UTF-16 code unit — encoding a string to UTF-16 hex here lets you verify a char array's contents match what the source text should produce.
A -> 0041
Common Mistakes When Converting Text to UTF-16 Hex
- Expecting the same byte count as UTF-8 — UTF-16 is wider for plain ASCII text.
- Forgetting emoji and other high code points need a 4-byte surrogate pair, not 2 bytes.
- Assuming byte order matches little-endian systems without checking — this output is big-endian.
Why Use This Instead of Doing It by Hand
- Handles surrogate pairs for emoji and other high code points automatically
- Runs entirely in your browser — nothing you type gets sent anywhere
- Saves you from manually splitting UTF-16 code units into byte pairs
- Matches the exact internal representation JavaScript, Java, and Windows APIs use
Limitations
- Encodes as big-endian, 2 bytes per code unit.
Frequently Asked Questions
How do you convert text to UTF-16 hex?
Each character becomes one or two 16-bit code units (2 bytes each) — most characters need one, characters above U+FFFF like emoji need a surrogate pair of two — written as hex, most significant byte first.
Why does this output more hex digits than UTF-8 for the same text?
UTF-16's baseline is 2 bytes per code unit even for plain ASCII characters, while UTF-8 uses just 1 byte for those same characters — English text roughly doubles in size going from UTF-8 to UTF-16.
What does this converter use for emoji?
A surrogate pair — two 2-byte code units (4 bytes total) that together represent the one character, following the same rule JavaScript uses internally for strings containing emoji.
Is the output big-endian or little-endian?
Big-endian — each code unit's high byte comes first. Some systems (notably Windows internals) use little-endian UTF-16 instead; swap each byte pair if you need that format.
Why would I need UTF-16 hex specifically?
Debugging raw string data from JavaScript, Java, or Windows APIs, all of which use UTF-16 internally — seeing the exact bytes helps track down encoding mismatches.
Is this the reverse of Hex to UTF-16?
Yes — that page decodes UTF-16 hex bytes back into readable text.
Is this the same as a "UTF-16LE converter"?
Related but not identical — UTF-16LE is the little-endian variant, with each code unit's bytes swapped compared to this converter's big-endian output. Reverse each 2-byte pair if you specifically need UTF-16LE.
Why does JavaScript's string.length lie for emoji?
Because JavaScript strings are UTF-16 internally, and .length counts 16-bit code units, not characters — an emoji needing a surrogate pair counts as 2 toward .length even though it's visually one character.