A diaeresis and an umlaut look identical: two dots sitting above a vowel. The difference is what the dots do. A diaeresis tells you to pronounce a vowel as its own syllable, as in naïve or Noël.
An umlaut marks a shifted vowel sound in German words like Müller. The diaeresis vs umlaut split matters for meaning, not for typing, because Unicode treats them as the same character and you type them the same way.
Diaeresis vs umlaut: the quick answer
Pick by what you mean, then type the glyph. Both marks share one set of characters on your keyboard and in Unicode, so the choice below is about intent, not input.
| If you mean… | Mark | Example |
|---|---|---|
| A vowel pronounced as a separate syllable | Diaeresis | naïve, Zoë, coöperate |
| A shifted German vowel sound | Umlaut | Müller, schön, für |
| Either one — you just need the character | Same glyph | ä ö ü ë ï ÿ |
What a diaeresis does
A diaeresis splits two vowels that would otherwise be read as one sound. In naïve, the dots on the i stop you from reading ai as a single vowel, so you say “nah-eev” rather than “nave.” Same job in Noël and the older spelling coöperate.
English uses it rarely and mostly in borrowed words and names. French, Spanish, and Dutch use it more often for the same reason: to force a vowel to stand alone. The mark never changes the vowel’s own sound, only whether it merges with its neighbour.
What an umlaut does
An umlaut changes the vowel’s sound outright. In German, a, o, and u gain fronted pronunciations as ä, ö, and ü. The word schon (“already”) and schön (“beautiful”) are different words because of those two dots.
The mark grew out of a small e once written above the vowel, which is why German keyboards treat ä ö ü as full letters rather than decorated ones. You will meet the umlaut in German, and in the same three vowels borrowed into other languages and brand names.
The differences people get wrong
There is no separate umlaut character in Unicode. Both marks share U+0308 COMBINING DIAERESIS, and the precomposed letters (ä, ö, ü, ë, ï, ÿ) carry the word “diaeresis” in their official names regardless of which purpose you use them for. Software cannot tell the two apart, so search, sorting, and spell-check treat Müller and a diaeresis-marked word the same way.
The overlap has limits. German has only ä ö ü, so ë and ï are almost always a diaeresis, never an umlaut.
And ÿ shows up mainly in a handful of French and Dutch names. Knowing which vowels each mark uses helps you spot a typo before it ships.
One more trap: the umlaut is not the same as the two dots in the heavy-metal band names (Motörhead, Mötley Crüe). Those are decorative and carry no phonetic meaning at all, which is why German speakers find them odd.
Reference table: every dotted vowel
These are the characters you need for both marks. The Alt codes are the reliable leading-zero form, which reads from the Windows-1252 set; use them exactly as written. The Word column is a hex code you type and then convert with Alt+X.
| Character | Unicode name | Unicode (hex) | Alt code (decimal) | Word (hex, then Alt+X) | HTML entity |
|---|---|---|---|---|---|
| Ä | U+00C4 | U+00C4 | Alt+0196 | 00C4 | Ä |
| ä | U+00E4 | U+00E4 | Alt+0228 | 00E4 | ä |
| Ë | U+00CB | U+00CB | Alt+0203 | 00CB | Ë |
| ë | U+00EB | U+00EB | Alt+0235 | 00EB | ë |
| Ï | U+00CF | U+00CF | Alt+0207 | 00CF | Ï |
| ï | U+00EF | U+00EF | Alt+0239 | 00EF | ï |
| Ö | U+00D6 | U+00D6 | Alt+0214 | 00D6 | Ö |
| ö | U+00F6 | U+00F6 | Alt+0246 | 00F6 | ö |
| Ü | U+00DC | U+00DC | Alt+0220 | 00DC | Ü |
| ü | U+00FC | U+00FC | Alt+0252 | 00FC | ü |
| Ÿ | U+0178 | U+0178 | Alt+0159 | 0178 | Ÿ |
| ÿ | U+00FF | U+00FF | Alt+0255 | 00FF | ÿ |
A note on the zero-less codes some sites publish, like the verified method shown in the table for Ä. Those read from your machine’s OEM code page, which is CP437 in the US but CP850 across the UK, Ireland, Canada, and Australia, so the same code can land on a different character for a different reader.
The leading-zero codes above avoid that. If you often need these letters, the on-screen accent keyboard skips codes entirely.
Type them on Windows
Hold Alt and type the decimal code from the table on the numeric keypad, then release Alt. For ü that is Alt+0252. This needs a real numeric keypad with Num Lock on; the top-row number keys will not work, and most laptops need Fn or an external pad.
No keypad handy? Press Win+.
to open the emoji panel, click the Ω symbols tab, and pick the letter from the Latin section. Character Map (search “charmap”) does the same job and shows the code for each glyph.
Type them on Mac
Mac has no Alt codes. Press Option+u (this arms the diaeresis), release, then type the vowel.
Option+u then u gives ü; Option+u then Shift+A gives Ä. The dead-key sequence covers every vowel in the table.
For anything Option+u will not produce, open the Character Viewer with Ctrl+Cmd+Space, search “diaeresis,” and double-click the letter you need.
Type them in Word, Excel, and PowerPoint
In Word, type the hex value then press Alt+X. Type 00FC, press Alt+X, and it flips to ü. This works in Word, Outlook, and OneNote, but not in Excel or PowerPoint. Word also has built-in shortcuts: Ctrl+Shift+colon then the vowel produces the dotted form.
Excel has no Alt+X. Use =UNICHAR(252) for ü, feeding it the decimal value, or paste the character. PowerPoint has neither Alt+X nor a formula bar, so use Insert > Symbol and pick the letter, or paste it in. Insert > Symbol works in all three programs and remembers your recent picks.
Type them in Google Docs and Sheets
In Google Docs, open Insert > Special characters, then either search “diaeresis” or draw the two-dot mark in the sketch box to find matches. Click the letter to drop it in.
Google Sheets has no special-character menu at all. Use =UNICHAR(252) in a cell for ü, or paste the letter. If you are typing an OS-level shortcut into a cell, press F2 first to enter edit mode.
Type them on phones and Chromebook
On iPhone and Android, press and hold the base vowel on the keyboard. A row of accented options pops up; slide to ä, ö, ü, ë, or ï and lift your finger. This is the fastest route on any touchscreen.
Chromebook has no Alt codes, and a USB numpad will not change that, because the feature is Windows software rather than keypad hardware. Press Ctrl+Shift+U, release, type the hex code (for example 00fc), then press Enter or Space.
An underlined u confirms input mode. The symbol picker at Launcher+Shift+Space is the fallback when a web field grabs the shortcut.
Type them in Notion, Slack, Discord, and Canva
None of these have a symbol menu for accented letters. The reliable move is to copy the character from the widget above and paste it. All four accept pasted Unicode without fuss.
To stop pasting repeatedly, set a text replacement in your operating system: map something like ;ue to ü (System Settings > Keyboard > Text on Mac, or Settings on iPhone and Android). The replacement then fires inside every app, these four included.
Precomposed vs combining marks
The letter ü can exist two ways that look identical on screen. One is the single precomposed character U+00FC.
The other is a plain u followed by the combining diaeresis U+0308, which stacks the dots onto the previous letter. Same picture, two different byte sequences.
This bites in real ways. A search for the precomposed form may miss the combined form, filenames that look the same may not match, and a form field can reject one while accepting the other. Copy-paste between systems sometimes swaps one for the other silently.
The fix is normalization. Converting text to NFC merges the two-part form back into single precomposed characters, which is what most databases and web forms expect. If a “correct-looking” word keeps failing a match, a stray combining mark is the usual culprit.
Troubleshooting
- Alt code does nothing: Num Lock is off, or you used the top-row numbers. Use the keypad, or the emoji panel at
Win+.. - Wrong character appears: you dropped the leading zero. Alt+0252 is ü; Alt+0252 reads from a different table and may give something else, especially outside the US.
- Dots show as an empty box: the font lacks that glyph. Ÿ and ÿ are the ones most likely to be missing; switch to a broad font like Arial, Calibri, or Segoe UI.
- Two words that look the same won’t match: one uses a combining mark. Normalize both to NFC before comparing.
- Option+u types a bare u on Mac: you released too early or are on a layout without the dead key. Press Option+u, let go, then the vowel — or use the Character Viewer.
Which one should you use
Writing German? It is an umlaut, on ä ö ü only. Marking an English, French, Dutch, or Spanish vowel to be read separately?
It is a diaeresis, and ë and ï are your common cases. The glyph you type is the same either way, so the decision is about spelling correctly, not about hunting for a second character.
For steady use across languages, learn the Mac Option+u dead key or the Windows leading-zero codes above. For occasional use, paste from the widget and set a text replacement.
Related guides
The complete guide to typing accented letters covers every mark and platform in one place, and the full library of accented-letter guides is worth a browse if you switch languages often.
If you are comparing diacritics, these three are the ones most often confused with the dots: the macron (ā ē ī ō ū), which is a straight bar rather than dots; the caron or háček (č š ž), a small v; and the enye (ñ), whose tilde is sometimes mistaken for stacked marks. The cedilla (ç) guide rounds out the set for anyone writing French or Portuguese.
Frequently asked questions
Are the diaeresis and umlaut the same character?
On a keyboard and in Unicode, yes. Both use the same characters (ä ö ü ë ï ÿ) and the same combining mark, U+0308. The difference is only in meaning: a diaeresis splits a syllable, an umlaut changes a vowel sound.
Why is ü called “with diaeresis” in Unicode if it’s a German umlaut?
Unicode names the mark once, by its shape, and reuses the character for both jobs. The official name “latin small letter u with diaeresis” applies whether you are writing German über or marking a separated vowel.
Can I type an umlaut without a numeric keypad?
Yes. On Windows use the emoji panel (Win+.
) or Character Map, on Mac use Option+u then the vowel, and on any phone long-press the vowel key. Alt codes are the only method that requires the keypad.
Why does the accented letter look different on my phone than on my laptop?
Font, not the code. The character is the same; your phone and laptop render it in different typefaces. If it shows as an empty box on one device, that font lacks the glyph, so switch to a common font like Arial or Segoe UI.
My search won’t find a word I know is spelled correctly. Why?
The text probably uses a combining diaeresis (letter plus U+0308) while your search uses the precomposed letter, or the reverse. They look identical but are different byte sequences. Normalizing the text to NFC usually fixes the mismatch.
Which vowels take a diaeresis versus an umlaut?
German umlauts appear only on a, o, and u (ä ö ü). A diaeresis can sit on more vowels, and ë and ï are the common English and French cases, with ÿ turning up in a few names.
Is the HTML entity the same for both marks?
Yes, because they are the same character. ü produces ü whether you intend an umlaut or a diaeresis. The numeric form ü works too and is safer for the rarer letters like Ÿ.