Copy ⌀ in one tap, or pick from 55 rows: Ø, ø, the null sign ∅, drawing signs and look-alikes.
Diameter Symbol Copy Paste
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55 diameter and null signs. Tap any value to copy it.
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55 diameter and null 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+2300. The sign a technical drawing puts before or after a number to say it is a diameter, as in ⌀ 55 mm. In Unicode since version 1.1 (1993), in the Miscellaneous Technical block. It has no Alt code, no Option key and no named HTML entity: write ⌀ in HTML.
U+00D8. A letter, not a diameter sign: Danish, Norwegian, Faroese and Southern Sámi use it. Unicode's alias: o slash. It has the keys ⌀ lacks: 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. Unicode's note: Danish, Norwegian, Faroese, IPA. Alt+0248 on a number pad, Option+O on a U.S. layout, ø in HTML and \o in LaTeX text.
U+2205. The set that has no elements. Unicode's alias: null set. The sign is credited to the Bourbaki group, André Weil in particular, in 1939, with the letter Ø as its model. ∅ in HTML, \varnothing in LaTeX with the amssymb package, and plain LaTeX has \emptyset.
Made of U+2300, U+0031 and U+0030. The diameter sign in front of a number, the way a drawing marks a hole of 10 mm diameter. Swap in your own number.
U+2298. A maths operator, a division slash inside a circle, and one of the characters the diameter sign is confused with. ⊘ in HTML and \oslash in LaTeX.
U+2400. A picture that stands for the null control code, U+0000, where the code itself cannot be shown. It sits in the Control Pictures block, 0x2400 above the code it pictures. It has no Alt code, entity or macro.
Made of U+0053 and U+2300. The letter S before the diameter sign. On a drawing it marks the diameter of a sphere, beside SR for a spherical radius.
U+2334. Unicode files it under Drafting symbols. A counterbore is a flat-bottomed hole that widens another hole, so that a screw head can sit flush with the surface or below it.
U+2335. The drafting sign for a countersink, a conical hole that lets the head of a countersunk screw sit flush with the surface or below it.
U+21A7. Unicode's alias: depth symbol. On a drawing the depth sign defines the depth of a feature. ↧ in HTML.
U+03A6. A Greek capital letter, a circle crossed by a vertical bar, often mistaken for the null sign. Alt+232 on a number pad, Φ in HTML and \Phi in LaTeX.
U+25A1. One of the most used dimensioning signs: it marks a square feature, as ⌀ marks a round one. □ in HTML. Its LaTeX macro needs the amssymb package.
U+23E4. Straightness among the geometric tolerance signs of an engineering drawing. Added in version 5.0 (2006). Unicode's alias is direct current symbol form one, so the character serves two trades.
U+23E5. Flatness among the geometric tolerance signs of an engineering drawing. Added in version 5.0 (2006). The HTML entity ▱ does not type it: that name belongs to ▱, White parallelogram.
U+25CB. Circularity among the geometric tolerance signs of an engineering drawing. Alt+9 on a number pad and ○ in HTML.
U+232D. Cylindricity among the geometric tolerance signs of an engineering drawing. Unicode files it under Drafting symbols. ⌭ in HTML.
U+2312. Profile of a line among the geometric tolerance signs of an engineering drawing. Unicode's alias: position of any line. ⌒ in HTML.
U+2313. Profile of a surface among the geometric tolerance signs of an engineering drawing. Unicode's alias: position of a surface. ⌓ in HTML.
U+27C2. Perpendicularity among the geometric tolerance signs of an engineering drawing. Unicode's alias: orthogonal to. Added in version 4.1 (2005). \perp in LaTeX.
U+2220. Angularity among the geometric tolerance signs of an engineering drawing. ∠ in HTML and \angle in LaTeX.
U+2225. Parallelism among the geometric tolerance signs of an engineering drawing. ∥ in HTML and \parallel in LaTeX.
U+232F. Symmetry among the geometric tolerance signs of an engineering drawing. The 2018 revision of the standard eliminated symmetry and concentricity.
U+2316. Position among the geometric tolerance signs of an engineering drawing. Unicode's alias: true position. ⌖ in HTML.
U+25CE. Concentricity among the geometric tolerance signs of an engineering drawing. It is the other sign that the 2018 revision eliminated.
U+2197. Circular run-out among the geometric tolerance signs of an engineering drawing. ↗ in HTML and \nearrow in LaTeX. It has the Emoji property, so an app may draw it in colour.
U+2330. Total run-out among the geometric tolerance signs of an engineering drawing. Unicode files it under Drafting symbols.
U+24C2. The modifier for maximum material condition in a feature control frame, the box that holds a geometric tolerance. It has the Emoji property, so an app may draw it in colour.
U+24C1. The modifier for least material condition in a feature control frame.
U+01FE. Ø with an acute accent. Unicode gives its make-up as Ø plus U+0301 and files it under Phonetic and historic letters.
U+01FF. The small letter of the pair: ø plus U+0301.
U+A74A. An O with a long stroke laid over it, one of the Medievalist additions of version 5.1 (2008).
U+A74B. The small letter of the pair, which Unicode cross-references to ø.
U+1D13. An ø turned on its side, in the Phonetic Extensions block since version 4.0 (2003).
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 and U+007D. A pair of braces with nothing between them is a common way to write the empty set. Both are keyboard characters.
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+03C6. The ordinary Greek small phi. Unicode's note: in mathematical contexts, the loopy glyph is preferred, to contrast with ϕ. Alt+237 on a number pad, φ in HTML and \varphi in LaTeX.
U+03D5. Unicode's note: used as a technical symbol, with a stroked glyph. ϕ in HTML, and in LaTeX it is this one that \phi prints.
U+0278. The phonetic alphabet's phi. Unicode's note: voiceless bilabial fricative.
U+0424. A Cyrillic capital, a circle crossed by a vertical bar, corresponding to f. Ф in HTML.
U+0444. The small letter of the pair. ф in HTML.
U+2349. A sign of the APL programming language, a circle with a backslash through it. Unicode cross-references it to ⦰.
U+233D. APL again, a circle with an upright stile through it. ⌽ in HTML.
U+29B8. A reverse solidus inside a circle, filed under Circle symbols. Added in version 3.2 (2002).
U+1F6AB. The emoji list calls it prohibited. The general prohibition sign is a red circle with a line from upper left to lower right inside it. Added in version 6.0 (2010).
U+2D41. A letter of Tifinagh, a script used to write the Berber languages, corresponding to h. One of the characters the diameter sign is confused with. Added in version 4.1 (2005).
Made of U+0030 and U+FE00. The digit zero plus the variation selector U+FE00. Unicode's name for the pair: short diagonal stroke form. The slash of a slashed zero usually stays inside the oval, unlike the stroke of Ø, ∅ and ⌀. Where a font has no such form, a plain 0 shows.
U+2BD0. Unicode cross-references it to ⌖, Position indicator, and files it under Miscellaneous symbols. Added in version 7.0 (2014).
U+AB3E. A blackletter o with a stroke. Unicode files it under Letters for German dialectology. Added in version 7.0 (2014).
U+1F6C7. Not in the emoji list. Unicode cross-references it to 🚫. Added in version 7.0 (2014).
The diameter symbol is ⌀, Diameter sign, U+2300. The 55 rows add the letter Ø and the empty set ∅ that it is confused with, the signs a drawing puts beside it, and labelled look-alikes.
Read the full guide
The signs that go with it
On a drawing ⌀ goes before the number, as in ⌀10, and S⌀ marks a sphere. ⌴ is a counterbore, ⌵ a countersink and ↧ the depth. The group Diameter and drawing signs adds the fourteen geometric tolerance signs, from ⏤ straightness to ⌰ total run-out, and the modifiers Ⓜ and Ⓛ.
Tips
▱ in HTML types ▱, a parallelogram, not ⏥ Flatness. No entity names ⌀ either, so write ⌀ or ⌀.
Slashed zero and Empty set, slashed zero form are 0 or ∅ plus U+FE00. Where a font has no such form, the plain character shows.
Questions and answers
How do I type the diameter symbol on a keyboard?
⌀ has no Alt code and no Option key, so copy it. With a Compose key, press Compose, d, i. The letter Ø has keys: Alt+0216 on a Windows number pad, or Option+Shift+O on a Mac with the U.S. layout.
Which is the null symbol to copy and paste?
Usually ∅, U+2205, Empty set, which Unicode also calls the null set. ␀, U+2400, Symbol for null, pictures the null control code instead. Both are in the first seven rows, and neither is the diameter sign.
What is the difference between ⌀, Ø and ∅?
⌀ is U+2300, Diameter sign, for technical drawings. Ø is U+00D8, a letter of Danish, Norwegian, Faroese and Southern Sámi. ∅ is U+2205, Empty set, which the Bourbaki group introduced in 1939 with Ø as its model. A search treats them as three characters.
What is the diameter symbol in HTML and LaTeX?
HTML has no name for ⌀, so write ⌀ or ⌀. In LaTeX, \diameter needs the wasysym package. Ø and \O print the letter Ø, and ∅ and \varnothing print ∅, the empty set.
⊘Circled division slashU+2298. A maths operator, a division slash inside a circle, and one of the characters the diameter sign is confused with. ⊘ in HTML and \oslash in LaTeX.
⌴CounterboreU+2334. Unicode files it under Drafting symbols. A counterbore is a flat-bottomed hole that widens another hole, so that a screw head can sit flush with the surface or below it.
⌵CountersinkU+2335. The drafting sign for a countersink, a conical hole that lets the head of a countersunk screw sit flush with the surface or below it.
⌀10Diameter of 10Made of U+2300, U+0031 and U+0030. The diameter sign in front of a number, the way a drawing marks a hole of 10 mm diameter. Swap in your own number.
⌀Diameter signU+2300. The sign a technical drawing puts before or after a number to say it is a diameter, as in ⌀ 55 mm. In Unicode since version 1.1 (1993), in the Miscellaneous Technical block. It has no Alt code, no Option key and no named HTML entity: write ⌀ in HTML.
↧Downwards arrow from barU+21A7. Unicode's alias: depth symbol. On a drawing the depth sign defines the depth of a feature. ↧ in HTML.
Show all 55 diameter and null signs (49 more)
Start here, continued
∅Empty setU+2205. The set that has no elements. Unicode's alias: null set. The sign is credited to the Bourbaki group, André Weil in particular, in 1939, with the letter Ø as its model. ∅ in HTML, \varnothing in LaTeX with the amssymb package, and plain LaTeX has \emptyset.
ΦGreek capital letter phiU+03A6. A Greek capital letter, a circle crossed by a vertical bar, often mistaken for the null sign. Alt+232 on a number pad, Φ in HTML and \Phi in LaTeX.
ØLatin capital letter O with strokeU+00D8. A letter, not a diameter sign: Danish, Norwegian, Faroese and Southern Sámi use it. Unicode's alias: o slash. It has the keys ⌀ lacks: 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. Unicode's note: Danish, Norwegian, Faroese, IPA. Alt+0248 on a number pad, Option+O on a U.S. layout, ø in HTML and \o in LaTeX text.
S⌀Spherical diameterMade of U+0053 and U+2300. The letter S before the diameter sign. On a drawing it marks the diameter of a sphere, beside SR for a spherical radius.
␀Symbol for nullU+2400. A picture that stands for the null control code, U+0000, where the code itself cannot be shown. It sits in the Control Pictures block, 0x2400 above the code it pictures. It has no Alt code, entity or macro.
Diameter and drawing signs 18
∠AngleU+2220. Angularity among the geometric tolerance signs of an engineering drawing. ∠ in HTML and \angle in LaTeX.
⌒ArcU+2312. Profile of a line among the geometric tolerance signs of an engineering drawing. Unicode's alias: position of any line. ⌒ in HTML.
◎BullseyeU+25CE. Concentricity among the geometric tolerance signs of an engineering drawing. It is the other sign that the 2018 revision eliminated.
ⓁCircled Latin capital letter LU+24C1. The modifier for least material condition in a feature control frame.
ⓂCircled Latin capital letter MU+24C2. The modifier for maximum material condition in a feature control frame, the box that holds a geometric tolerance. It has the Emoji property, so an app may draw it in colour.
⌭CylindricityU+232D. Cylindricity among the geometric tolerance signs of an engineering drawing. Unicode files it under Drafting symbols. ⌭ in HTML.
⏥FlatnessU+23E5. Flatness among the geometric tolerance signs of an engineering drawing. Added in version 5.0 (2006). The HTML entity ▱ does not type it: that name belongs to ▱, White parallelogram.
↗North east arrowU+2197. Circular run-out among the geometric tolerance signs of an engineering drawing. ↗ in HTML and \nearrow in LaTeX. It has the Emoji property, so an app may draw it in colour.
∥Parallel toU+2225. Parallelism among the geometric tolerance signs of an engineering drawing. ∥ in HTML and \parallel in LaTeX.
⟂PerpendicularU+27C2. Perpendicularity among the geometric tolerance signs of an engineering drawing. Unicode's alias: orthogonal to. Added in version 4.1 (2005). \perp in LaTeX.
⌖Position indicatorU+2316. Position among the geometric tolerance signs of an engineering drawing. Unicode's alias: true position. ⌖ in HTML.
⌓SegmentU+2313. Profile of a surface among the geometric tolerance signs of an engineering drawing. Unicode's alias: position of a surface. ⌓ in HTML.
⯐Square position indicatorU+2BD0. Unicode cross-references it to ⌖, Position indicator, and files it under Miscellaneous symbols. Added in version 7.0 (2014).
⏤StraightnessU+23E4. Straightness among the geometric tolerance signs of an engineering drawing. Added in version 5.0 (2006). Unicode's alias is direct current symbol form one, so the character serves two trades.
⌯SymmetryU+232F. Symmetry among the geometric tolerance signs of an engineering drawing. The 2018 revision of the standard eliminated symmetry and concentricity.
⌰Total runoutU+2330. Total run-out among the geometric tolerance signs of an engineering drawing. Unicode files it under Drafting symbols.
○White circleU+25CB. Circularity among the geometric tolerance signs of an engineering drawing. Alt+9 on a number pad and ○ in HTML.
□White squareU+25A1. One of the most used dimensioning signs: it marks a square feature, as ⌀ marks a round one. □ in HTML. Its LaTeX macro needs the amssymb package.
The letter Ø 6
ꝊLatin capital letter O with long stroke overlayU+A74A. An O with a long stroke laid over it, one of the Medievalist additions of version 5.1 (2008).
ǾLatin capital letter O with stroke and acuteU+01FE. Ø with an acute accent. Unicode gives its make-up as Ø plus U+0301 and files it under Phonetic and historic letters.
ꬾLatin small letter blackletter o with strokeU+AB3E. A blackletter o with a stroke. Unicode files it under Letters for German dialectology. Added in version 7.0 (2014).
ꝋLatin small letter o with long stroke overlayU+A74B. The small letter of the pair, which Unicode cross-references to ø.
ǿLatin small letter o with stroke and acuteU+01FF. The small letter of the pair: ø plus U+0301.
ᴓLatin small letter sideways o with strokeU+1D13. An ø turned on its side, in the Phonetic Extensions block since version 4.0 (2003).
Empty set and null 7
{}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 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.
∅︀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.
⦰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.
Look-alikes 12
⍉APL functional symbol circle backslashU+2349. A sign of the APL programming language, a circle with a backslash through it. Unicode cross-references it to ⦰.
⌽APL functional symbol circle stileU+233D. APL again, a circle with an upright stile through it. ⌽ in HTML.
⦸Circled reverse solidusU+29B8. A reverse solidus inside a circle, filed under Circle symbols. Added in version 3.2 (2002).
ФCyrillic capital letter efU+0424. A Cyrillic capital, a circle crossed by a vertical bar, corresponding to f. Ф in HTML.
фCyrillic small letter efU+0444. The small letter of the pair. ф in HTML.
ϕGreek phi symbolU+03D5. Unicode's note: used as a technical symbol, with a stroked glyph. ϕ in HTML, and in LaTeX it is this one that \phi prints.
φGreek small letter phiU+03C6. The ordinary Greek small phi. Unicode's note: in mathematical contexts, the loopy glyph is preferred, to contrast with ϕ. Alt+237 on a number pad, φ in HTML and \varphi in LaTeX.
ɸLatin small letter phiU+0278. The phonetic alphabet's phi. Unicode's note: voiceless bilabial fricative.
🚫No entry signU+1F6AB. The emoji list calls it prohibited. The general prohibition sign is a red circle with a line from upper left to lower right inside it. Added in version 6.0 (2010).
🛇Prohibited signU+1F6C7. Not in the emoji list. Unicode cross-references it to 🚫. Added in version 7.0 (2014).
0︀Slashed zeroMade of U+0030 and U+FE00. The digit zero plus the variation selector U+FE00. Unicode's name for the pair: short diagonal stroke form. The slash of a slashed zero usually stays inside the oval, unlike the stroke of Ø, ∅ and ⌀. Where a font has no such form, a plain 0 shows.
ⵁTifinagh letter berber academy yahU+2D41. A letter of Tifinagh, a script used to write the Berber languages, corresponding to h. One of the characters the diameter sign is confused with. Added in version 4.1 (2005).