Mathematical symbol Empty Set
About this character
The character ∅ carries the official Unicode name “Mathematical symbol Empty Set” and the code point U+2205, which is 8709 in decimal. It belongs to the Mathematical Operators block (U+2200–U+22FF), which gathers the operators, quantifiers and relations of algebra, logic and set theory.
In memory, ∅ takes 3 bytes in UTF-8 (0xE2 0x88 0x85) and 1 in UTF-16 (0x2205). That difference is why badly configured forms or databases garble this character: they assume one byte per character.
How to type ∅
| System | What to do |
|---|---|
| Windows | In Word or WordPad, type 2205 and press Alt + X to turn the code into the character. |
| macOS | On a Mac, open the Character Viewer with Ctrl + ⌘ + Space and search for “Mathematical symbol Empty Set”. |
| Linux | On Linux (GTK), type Ctrl + ⇧ + U, 2205 then press Enter. |
| HTML / Web | In an HTML page, write ∅. Use \2205 in CSS, \u2205 in JavaScript and \u2205 in Python. |
| On this site | The simplest route is the Copy button above: the character goes straight to your clipboard, ready to paste anywhere. |
Keyboards that include ∅
This character sits directly on the following ClavierVirtuel layouts, where you can click it with the mouse:
Codes and encodings
| Property | Value |
|---|---|
| Code point | U+2205 |
| Unicode block | Mathematical Operators (U+2200–U+22FF) |
| Decimal | 8709 |
| Hexadecimal | 0x2205 |
| Octal | 021005 |
| Binary | 10001000000101 |
| UTF-8 bytes | 0xE2 0x88 0x85 |
| UTF-16 units | 0x2205 |
| Named HTML entity | ∅ |
| Decimal HTML entity | ∅ |
| Hex HTML entity | ∅ |
| CSS escape | \2205 |
| JavaScript escape | \u2205 |
| Python escape | \u2205 |
| URL encoding | %E2%88%85 |
Frequently asked questions
What is the Unicode code for ∅?
Its code point is U+2205, which is 8709 in decimal and 021005 in octal. In HTML you can write it as ∅ or ∅.
Why does ∅ show up as a box or a question mark?
An empty box means the font has no glyph for U+2205. The character is still in the text: switching to a font that covers the block (Noto, DejaVu or Segoe UI Symbol) makes it appear.
Can I use ∅ in a filename, a URL or a password?
In a URL it must be encoded as %E2%88%85. Modern filesystems accept it, though it is still risky when moving files between systems. For passwords, some forms reject non-ASCII characters outright.