Empty Set Symbol (∅)

The empty set symbol ∅ is Unicode U+2205, the slashed circle for a set with no elements. Press Copy to put it on your clipboard.

Unicode: U+2205
HTML: ∅
Word: 2205 Alt+X

How to type the empty set symbol (∅)

The quickest way is to press Copy above and paste. To type ∅ yourself, use the method for your device below.

Windows

In Word or Outlook, type 2205 and press Alt + X. Alt + X converts the hex code before the cursor into the character, and back again.
Press Win + R, type charmap and press Enter. Tick “Advanced view”, search for Empty Set, then Select and Copy. Character Map is built into every version of Windows.

Mac

Press Control + Command + Space to open the Character Viewer, search for empty set and double-click it.
With the Unicode Hex Input keyboard enabled (System Settings → Keyboard → Input Sources), hold Option and type 2205.

Linux & ChromeOS

Press Ctrl + Shift + U, type 2205, then press Enter or Space. Works in GTK and IBus apps (GNOME, Firefox, Chrome, LibreOffice) and on ChromeOS.

iPhone & iPad

Copy ∅ from this page, then go to Settings → General → Keyboard → Text Replacement and add it with a shortcut such as ;empt. The shortcut then turns into the symbol as you type, in every app.

Android

Copy ∅ here, then open Gboard settings → Dictionary → Personal dictionary and add it with a shortcut.

Microsoft Word

Type 2205, then press Alt + X.
Insert → Symbol → More Symbols. Set “from” to Unicode (hex), type 2205 in “Character code” and click Insert.

Google Docs

Insert → Special characters, then search for “empty set” or draw it in the box.

Excel & Google Sheets

Enter =UNICHAR(8709) in a cell. It works in Excel 2013 and later and in Google Sheets.

HTML

Write ∅ or ∅ in your HTML.

What does ∅ mean?

∅ is the empty set, the unique set with no elements. The Bourbaki group introduced it in 1939; André Weil later explained that he borrowed the shape from the Norwegian letter Ø. It is equivalent to writing {}, and it is a subset of every set, which is why ∅ ⊂ A is always true.

Because it looks so similar to other slashed circles, ∅ is frequently mixed up with them. The letter Ø (as in the Danish øl), the diameter sign ⌀ on engineering drawings and the “slashed zero” used on old terminals are all different characters. Choose ∅ only when you mean the set with nothing in it.

In probability ∅ is the impossible event, with P(∅) = 0, and in linguistics it can mark a “null” or silent element.

Common uses

Set theory: A ∩ B = ∅ (A and B have nothing in common)
Solutions with no answers: the solution set is ∅
Probability: the impossible event ∅

Empty Set Symbol codes for HTML, CSS and programming

Every code below produces ∅. Use the HTML entity in web pages, the CSS escape in content, and the escape sequence in source code.

Codes for ∅
Unicode code point	`U+2205`
HTML entity (named)	`∅`
HTML decimal	`∅`
HTML hex	`∅`
CSS content	`content: "\2205";`
JavaScript	`"\u2205"`
Python	`"\u2205"`
Python (by name)	`"\N{EMPTY SET}"`
Java / C#	`"\u2205"`
LaTeX	`\emptyset`
UTF-8 bytes	`E2 88 85`
UTF-16	`2205`
URL encoded	`%E2%88%85`

∅ vs look-alike characters

These characters look similar to ∅ but have a different meaning and code. Pasting the wrong one can break search, sorting and screen readers.

Char	Name	When to use it
	Capital O with Stroke `U+00D8`	Latin capital letter O with stroke, a Danish and Norwegian vowel.
	Diameter `U+2300`	Diameter sign, for pipe and hole sizes on drawings (⌀ 20 mm).
	Greek capital Phi `U+03A6`	Greek capital phi, sometimes used by mistake for the empty set.
	Digit Zero `U+0030`	The digit zero. Some fonts show a slashed zero, but it is still a digit.

Symbols similar to ∅

Click to copy, or open a symbol for its codes. See the full math symbols collection.

∅ character properties

Official Unicode name: EMPTY SET
Also known as: null set, empty set, void set
Code point: U+2205
Unicode block: Mathematical Operators (U+2200–U+22FF)
General category: Math symbol (Sm)
Added in: Unicode 1.1 (1993)
Plane: Basic Multilingual Plane (0)
Emoji: No, it is a text symbol

Frequently asked questions

Is ∅ the same as {}?

Yes. Both denote the empty set. {∅}, however, is a set that contains one element, the empty set, so it is not empty.

Is ∅ the same as the diameter symbol?

No. The diameter sign ⌀ (U+2300) belongs on technical drawings; ∅ (U+2205) is for set theory.

Is there an alt code for the empty set symbol?

No. ∅ is outside the Windows-1252 and code page 437 character sets, so no Alt + number code produces it. Copy it from this page, type 2205 then Alt + X in Word, or find it in Character Map.

How do I type the empty set symbol on a Mac?

There is no single Option shortcut for ∅ on the US layout. Press Control + Command + Space to open the Character Viewer, search for “empty set” and double-click it, or copy it from this page.

What is the HTML code for the empty set symbol?

Use the named entity ∅ or the numeric reference ∅ (hex ∅). All three display ∅ in every browser.

What is the Unicode for the empty set symbol?

∅ is U+2205, officially named EMPTY SET, in the Mathematical Operators block. It has been part of Unicode since version 1.1 (1993).