How to type Capital Alpha
To type Capital Alpha (Α), press Alt + 913 on Windows, holding Alt while typing the digits on the numeric keypad, or write Α in HTML. On any system you can copy it from this page, or enter its codepoint U+0391 directly: Ctrl+Shift+U then 0391 on Linux, or 0391 then Alt+X in Microsoft Word.
Greek Capital Letter Alpha
- Copy it
- Unicode
- U+0391
- Windows
- Alt + 913 needs regedit
| Where | Shortcut | How |
|---|---|---|
| Windows | Alt + 913 | Above 255, so Windows will not accept it as typed. Copy the character instead. |
| Mac | N/A | Press the keys together. |
| HTML | Α | Paste this into HTML source. |
| Unicode | U+0391 | GREEK CAPITAL LETTER ALPHA |
Other greek symbols
Α lives in the Greek and Coptic block (U+0370-U+03FF), the Greek alphabet, used throughout mathematics and the sciences. Within Unicode it is classified as Lu, an uppercase letter. It has a lowercase counterpart and changes under case conversion. Its bidirectional class makes it left-to-right.
Its lowercase counterpart is α (U+03B1). They are separate codepoints, so a byte comparison treats them as different characters even though a case-insensitive search does not.
What Capital Alpha is used for
In mathematical notation Α is a variable: it stands for a quantity rather than acting on one, so an equation treats it the way it treats x, and the spacing around it is the spacing around a letter. That is the classification unicode-math gives it, and it is what decides how the symbol is set: $\mupAlpha$ in LaTeX, in maths mode rather than in a sentence.
Α is a letter before it is a symbol, and on the Greek keyboard layout it is simply Shift and A: the key your keycap already calls A. That is the route when you are typing Greek rather than reaching for one character. How to type Greek on a keyboard has the whole map.
What Α gets confused with
Unicode's own confusables table, the one used to catch lookalike domain names, groups Α with A (U+0041, Latin Capital Letter A). They are separate characters that render close enough to be mistaken for one another, so a search or a string comparison will separate them where your eye will not. If Capital Alpha is not matching where you expect it to, one of these is the usual reason.
How Capital Alpha behaves in software
Α is East Asian Ambiguous: one column in a Western locale and two in a CJK one. That is why a table that lines up on your machine can break on somebody else's, with no change to the text at all. It is a left-to-right character, so it holds that direction even inside a right-to-left paragraph.
Every way to write Capital Alpha
| Form | Value |
|---|---|
| Codepoint | U+0391 |
| Decimal | 913 |
| UTF-8 bytes | CE 91 |
| UTF-16 bytes | 03 91 |
| HTML entity | Α |
| HTML numeric | Α or Α |
| CSS | \0391 |
| JavaScript | \u0391 |
| Python | \u0391 |
| URL-encoded | %CE%91 |
| LaTeX, in maths mode | $\mupAlpha$ |
| SVG | 0391.svg · (SIL Open Font License) |
If Α arrives as Α
That is this exact character, undamaged: its two UTF-8 bytes CE 91 are being read one at a time as Windows-1252. The Latin-1 range is where this happens most, because it is the range every legacy system thought it already handled. Nothing is lost, and retyping will not help: the fix is at the reading end, which has to be told the text is UTF-8. An empty rectangle is the opposite complaint, and means the encoding is right and the font has no glyph for U+0391.