Copy ∅, the null set or empty set symbol: neither Alt code table holds it, and Alt+0216 types Ø.
Null Set Alt Code
∅Empty setU+2205Ready to copy
24 empty set signs. Tap any value to copy it.
24 empty set signs. A character and its name both copy the character. A code copies the code.
Character
Name
Code point
Alt code
Option keys
HTML
LaTeX
U+2205. The set with no members. Unicode's other name for it: null set. It is in neither Alt code table. ∅ in HTML, \emptyset in LaTeX, and \varnothing with the amssymb package.
Made of U+007B and U+007D. A pair of braces with nothing between them is a common way to write the empty set. Both are keyboard characters.
Made of U+2205 and U+FE00. ∅ plus the variation selector U+FE00. Unicode's name for the pair: zero with long diagonal stroke overlay form. The slashed zero form of the empty set that TeX made familiar. Where a font has no such form, the plain ∅ shows.
Made of U+007B, U+2205 and U+007D. A set with one member, the empty set, so it is not empty itself. The power set of ∅ is this set.
Made of U+2260 and U+2205. After the name of a set it says the set has at least one member: A≠∅.
Made of U+2205, U+2286 and the letter A. True whatever the set A is: any set includes the empty set.
U+29B0. The empty set with its slash reversed. Unicode files five such signs under Empty sets, all added in version 3.2 (2002). ⦰ in HTML.
U+29B1. The empty set with a bar over it. ⦱ in HTML.
U+29B2. The empty set with a small circle above it. ⦲ in HTML.
U+29B3. The empty set with an arrow above it that points right. ⦳ in HTML.
U+29B4. The empty set with an arrow above it that points left. ⦴ in HTML.
U+2209. Not an element of. Whatever x is, x∉∅ holds, because the empty set has no members. ∉ in HTML and \notin in LaTeX.
U+2286. Subset of or equal to. The empty set is a subset of every set, and its only subset is itself. ⊆ in HTML and \subseteq in LaTeX.
U+222A. Union. Any set A united with the empty set gives A again. ∪ in HTML and \cup in LaTeX.
U+2229. Intersection. Any set A intersected with the empty set gives the empty set. Alt+239 on a number pad, ∩ in HTML and \cap in LaTeX.
Made of the letter A, U+222A and U+2205. It equals A: joining nothing to a set leaves the set as it was.
Made of the letter A, U+2229 and U+2205. It equals ∅: a set shares no member with a set that has none.
U+2400. A picture that stands for the null control code, U+0000, where the code itself cannot be shown: null in the computing sense, and not a set.
U+2300. The diameter sign of a technical drawing. Unicode lists it and the empty set as look-alikes of each other.
U+00D8. A letter of the Danish and Norwegian alphabets, and the model the empty set sign was drawn from. Alt+0216 on a number pad, Option+Shift+O on a U.S. layout, Ø in HTML and \O in LaTeX text.
U+00F8. The small letter of the pair. Alt+0248 on a number pad, Option+O on a U.S. layout, ø in HTML and \o in LaTeX text.
U+03A6. The Greek capital phi: a circle crossed by an upright bar, where ∅ has a slash. Alt+232 on a number pad, Φ in HTML and \Phi in LaTeX.
U+03C6. The Greek small phi, a letter and not a set sign. Alt+237 on a number pad, φ in HTML and \varphi in LaTeX.
U+0030. The digit zero, on the keyboard. It was once written for the empty set, a use now held to be improper.
The null set symbol is ∅, Empty set, U+2205. It is in neither Alt code table, so no number-pad code types it: Alt+0216 gives the letter Ø and Alt+237 the Greek φ. Copy ∅, or write ∅ in HTML.
Read the full guide
The empty set symbol on a keyboard
No key of the U.S. keyboard carries ∅, and no Option key types it. With a Compose key, press Compose, then { and }. LaTeX writes \emptyset, or \varnothing with the amssymb package.
What the symbol represents in math
∅ is the set with no members, and its size is zero. Set theory, a topic of discrete math, also writes it as empty braces, {}. It is a subset of every set, and nothing is an element of it.
The sign dates from 1939 and was modelled on Ø, a letter of the Danish and Norwegian alphabets.
The slashed circle on a drawing is ⌀, the diameter sign, U+2300: another character.
{∅} is not empty. It is a set with one member, the empty set.
Questions and answers
What is the Alt code for the null set?
There is no number-pad code for it: ∅ is in neither Alt code table. Alt+0216 types Ø and Alt+237 types φ, two look-alikes. In apps that read a code above 255 as a code point, Alt+8709 types ∅.
What Greek letter denotes the empty set?
None. ∅ is a mathematical symbol and not a Greek letter, though it is often taken for phi, Φ or φ. A set that is not empty is written A≠∅, with no letter of its own.
What does the symbol for an empty set look like in math?
A circle with a slash through it, drawn from lower left to upper right. Some fonts make it a narrow zero with a long slash. ⦰, the reversed empty set, has the slash the other way.
Which is the null symbol to copy and paste?
Usually ∅, U+2205, which Unicode names Empty set and also calls the null set. ␀, U+2400, pictures the null control code of computing. In measure theory a null set is a set of measure zero, which need not be empty.
All 24 empty set signs
Start here 6
{}Empty bracesMade of U+007B and U+007D. A pair of braces with nothing between them is a common way to write the empty set. Both are keyboard characters.
∅Empty setU+2205. The set with no members. Unicode's other name for it: null set. It is in neither Alt code table. ∅ in HTML, \emptyset in LaTeX, and \varnothing with the amssymb package.
∅⊆AEmpty set, a subset of AMade of U+2205, U+2286 and the letter A. True whatever the set A is: any set includes the empty set.
∅︀Empty set, slashed zero formMade of U+2205 and U+FE00. ∅ plus the variation selector U+FE00. Unicode's name for the pair: zero with long diagonal stroke overlay form. The slashed zero form of the empty set that TeX made familiar. Where a font has no such form, the plain ∅ shows.
≠∅Is not emptyMade of U+2260 and U+2205. After the name of a set it says the set has at least one member: A≠∅.
{∅}Set that holds the empty setMade of U+007B, U+2205 and U+007D. A set with one member, the empty set, so it is not empty itself. The power set of ∅ is this set.
Show all 24 empty set signs (18 more)
Empty set forms 5
⦴Empty set with left arrow aboveU+29B4. The empty set with an arrow above it that points left. ⦴ in HTML.
⦱Empty set with overbarU+29B1. The empty set with a bar over it. ⦱ in HTML.
⦳Empty set with right arrow aboveU+29B3. The empty set with an arrow above it that points right. ⦳ in HTML.
⦲Empty set with small circle aboveU+29B2. The empty set with a small circle above it. ⦲ in HTML.
⦰Reversed empty setU+29B0. The empty set with its slash reversed. Unicode files five such signs under Empty sets, all added in version 3.2 (2002). ⦰ in HTML.
Set signs beside it 6
∩IntersectionU+2229. Intersection. Any set A intersected with the empty set gives the empty set. Alt+239 on a number pad, ∩ in HTML and \cap in LaTeX.
A∩∅Intersection with the empty setMade of the letter A, U+2229 and U+2205. It equals ∅: a set shares no member with a set that has none.
∉Not an element ofU+2209. Not an element of. Whatever x is, x∉∅ holds, because the empty set has no members. ∉ in HTML and \notin in LaTeX.
⊆Subset of or equal toU+2286. Subset of or equal to. The empty set is a subset of every set, and its only subset is itself. ⊆ in HTML and \subseteq in LaTeX.
∪UnionU+222A. Union. Any set A united with the empty set gives A again. ∪ in HTML and \cup in LaTeX.
A∪∅Union with the empty setMade of the letter A, U+222A and U+2205. It equals A: joining nothing to a set leaves the set as it was.
Not the empty set 7
⌀Diameter signU+2300. The diameter sign of a technical drawing. Unicode lists it and the empty set as look-alikes of each other.
0Digit zeroU+0030. The digit zero, on the keyboard. It was once written for the empty set, a use now held to be improper.
ΦGreek capital letter phiU+03A6. The Greek capital phi: a circle crossed by an upright bar, where ∅ has a slash. Alt+232 on a number pad, Φ in HTML and \Phi in LaTeX.
φGreek small letter phiU+03C6. The Greek small phi, a letter and not a set sign. Alt+237 on a number pad, φ in HTML and \varphi in LaTeX.
ØLatin capital letter o with strokeU+00D8. A letter of the Danish and Norwegian alphabets, and the model the empty set sign was drawn from. Alt+0216 on a number pad, Option+Shift+O on a U.S. layout, Ø in HTML and \O in LaTeX text.
øLatin small letter o with strokeU+00F8. The small letter of the pair. Alt+0248 on a number pad, Option+O on a U.S. layout, ø in HTML and \o in LaTeX text.
␀Symbol for nullU+2400. A picture that stands for the null control code, U+0000, where the code itself cannot be shown: null in the computing sense, and not a set.