Combining diaeresis is the Unicode character at U+0308 in the Combining Diacritical Marks block. Official name: COMBINING DIAERESIS. It is a combining mark (also called an umlaut mark) that attaches to the previous base letter — for example ü → ü.
Remember
Mark (combining ̈)
Unicode U+0308
Hex entity ̈
Decimal ̈
CSS escape \0308
Named entity (none for U+0308)
Prefer when ä ö ü exist
For German and other common letters, prefer precomposed entities (ä, ö, ü, ë). Use combining U+0308 when no precomposed form exists.
Combining diaeresis rendered with base letters and precomposed forms.
Built with U+0308ä ö ü ë
Precomposedä ö ü ë
Word exampleMünchen, schön, über
Comparedü ü ¨
With entitiesHex: ü | Decimal: ü | Named: ü
Code
Complete HTML Example
One page that shows combining diaeresis with hex, decimal, CSS escape, a built letter, and a precomposed alternative. Use View Output or open the live editor.
Hex + Decimal + CSS + Built + Precomposed
Ways to work with U+0308 and the preferred ü form.
Built with Hex: ü
Built with Decimal: ü
Built with CSS: ü
Precomposed (preferred): ü
German: München
How It Works
1. Hex: write a base letter, then ̈. The mark combines → ü.
2. Decimal: same mark as 776 → ü. Same visual as hex.
3. CSS: put the base letter and \0308 together in content (e.g. "u\0308"). Combining alone in content has nothing to attach to.
4. Precomposed:ü is one character (U+00FC). Prefer this for everyday ü.
Pitfalls & Tips
Common mistakes when working with Combining Diaeresis.
Order
Base letter first
Write the letter, then the mark: ü. A lone ̈ has nothing to combine with.
Prefer
Use precomposed when you can
ü is simpler, more searchable, and better supported than building ü.
¨
Not spacing diaeresis
¨ / ¨ is U+00A8 (standalone ¨). It does not attach to letters like U+0308.
CSS vs HTML
Do not mix escapes
\0308 belongs in CSS strings. ̈ / ̈ belong in HTML.
NFC
Normalization
ü and ü can look identical but differ in code points. Normalize (NFC) when comparing strings.
Semicolon
End references
Always finish with ; — write ̈, not ̈.
Compatibility
Browser Support
Combining diaeresis (U+0308) and its numeric entity forms (̈, ̈, CSS \\0308) are supported in all mainstream browsers. Rendering quality depends on font combining-mark support.
✓ Universal support
Combining Diaeresis (U+0308)
Encode with hex, decimal, or CSS escape after a base letter — prefer precomposed forms for common letters.
100%Browser coverage
Google ChromeSupported
Yes
Microsoft EdgeSupported
Yes
Mozilla FirefoxSupported
Yes
Apple SafariSupported
Yes
OperaSupported
Yes
Internet ExplorerAll versions
Yes
U+0308 / entitiesFull support
Bottom line: Use ̈ or ̈ after a base letter when you need the combining mark. Prefer ä / ö / ü for everyday text. Use \\0308 only inside CSS content.
Remember
Key Takeaways
Unicode: combining diaeresis is U+0308 (decimal 776) — attaches to the previous letter.
HTML: use ̈ / ̈ after a base letter (no named entity for U+0308).
CSS: use a letter plus \0308 inside content (e.g. "u\0308").
Default: prefer ä / ö / ü over building with U+0308.
One line:U+0308 → base + ̈ / ̈ / CSS \0308 — or use ü when you can.
Frequently Asked Questions
Use ̈ (hex), ̈ (decimal), or the CSS escape \0308 in content after a base letter. There is no named HTML entity for U+0308. For common letters prefer precomposed forms like ä ö ü.
U+0308 (COMBINING DIAERESIS). Hex 0308, decimal 776. It belongs to the Combining Diacritical Marks block (U+0300–U+036F).
No. Use numeric references like ̈ or ̈. Spacing diaeresis uses ¨ or ¨ (U+00A8) — that is a different character.
Prefer precomposed entities (ä ö ü ë) for everyday text. Use combining U+0308 when you need a letter that has no precomposed form, or when building diacritics dynamically.
HTML entities (̈ or ̈) go in markup after a base character. The CSS escape \0308 goes in stylesheet strings (usually content on ::before/::after).
U+0308 combines with the previous letter. U+00A8 (¨ / ¨) is a standalone spacing character and does not automatically attach to a letter.
🤔
Did you know?
Combining diaeresis is Unicode U+0308 (decimal 776). It is a combining mark that attaches to the previous character (e.g. ü → ü). HTML5 has no named entity for U+0308. Prefer precomposed letters like ü when they exist.
