Structural drawings are full of diameters: Ø16@200, 2Ø22, a Ø110 pipe. The symbol is not on the keyboard, so how to type the diameter symbol in AutoCAD is one of the first questions beginners ask. The short answer is %%c. The full answer is longer, because the same code draws a different shape in each font.
This article tries four ways of typing the diameter symbol, plus the two codes that usually come with it, degrees and plus/minus, in three fonts: Arial, romans.shx and txt.shx. Every result was exported to PDF and read back, and the image above is cropped straight from that PDF, AutoCAD 2027. Text in general is covered in text in AutoCAD. For drawing presentation taught properly, the Institute runs an AutoCAD course for construction.
How to type the diameter symbol: %%c
When TEXT or MTEXT asks for the content, type %%c16 and you get Ø16. The two percent signs tell AutoCAD that the next character is a control code, not plain text. The Autodesk control codes reference lists %%c as the code that draws the diameter symbol.
| Type | Shows | Used for |
|---|---|---|
%%c16 | Ø16 | Diameters, rebar, pipes |
%%C16 | Ø16 | Upper case works too, same result |
%%d45 | °45 | Degrees |
%%p5 | ±5 | Plus/minus, e.g. level ±0.000 |
Lower or upper case gives the same shape in all three fonts. In a TEXT object AutoCAD keeps the string %%c16 as typed; it only becomes the symbol when drawn.
The Unicode code \U+2205
The second way is the Unicode code \U+2205, the official "diameter sign" character. It is also the code DIMDIAMETER inserts in front of the value in a diameter dimension; see radius dimensions in AutoCAD.
In SHX fonts \U+2205 draws exactly the same shape as %%c: a small circle with a slash. Unlike %%c, the string \U+2205 is stored as the code itself.
One code, two shapes
This is what most tutorials skip. Look at the %%c column in the image: it gives two quite different shapes.
| Font | %%c16 draws | In the PDF |
|---|---|---|
| Arial | The letter Ø, as tall as a capital | Character U+00D8, searchable and copyable |
romans.shx | The diameter sign: a small slashed circle | Strokes, plus a comment %%c16 |
txt.shx | The diameter sign, coarser strokes | Strokes, plus a comment %%c16 |
Arial has no separate diameter-sign glyph, so in that font %%c, %%C and \U+2205 all draw the letter Ø. On a print the reader still understands, but next to SHX text the two kinds of diameter look untidy in one drawing.
For a consistent drawing, choose one text style for all rebar notes and keep it. If the drawing has accented text, such as Vietnamese, a TrueType font such as Arial is required, because SHX fonts usually lack those accents, and the diameter will then be the letter Ø.
The letter Ø: the easiest mistake
Many people copy an Ø from Word or a web page and paste it into AutoCAD. That character is U+00D8, a letter of the Danish and Norwegian alphabets, not the diameter sign. Typing the code \U+00D8 makes AutoCAD store the real letter Ø in the object.
| Font | \U+00D8 16 draws |
|---|---|
| Arial | Ø, identical to %%c |
romans.shx | A tall, oval letter Ø, clearly unlike the diameter sign next to it |
txt.shx | A tall letter Ø, clearly unlike the diameter sign |
In Arial there is no visible difference, so the mistake lies dormant until someone switches the style to an SHX font. Then the notes typed with %%c become neat diameter signs and the pasted ones become tall letters, and the rebar schedule shows two kinds of diameter. The safe habit is always %%c.
Common rebar notes
%%c can go anywhere in a line of text, not only at the start, and several codes can share one line. A few patterns for structural notes, each typed at the text content prompt exactly as shown.
| To show | Type |
|---|---|
| Ø16@200 | %%c16@200 |
| 2Ø22 | 2%%c22 |
| 4Ø18 + 2Ø16 | 4%%c18 + 2%%c16 |
| Level ±0.000 | %%p0.000 |
| Roof pitch 30° | Roof pitch 30%%d |
A diameter on a linear dimension: %%c<>
A pipe seen from the side, a round column in elevation or a bar drawn lengthwise is just two parallel lines, so it takes a linear DIMLINEAR dimension, and AutoCAD adds no diameter sign. At the text placement prompt, choose T (Text) and type %%c<>.
With the lines 800 apart the dimension shows Ø800. The <> pair keeps the true measurement, so if the lines move apart the value updates and the diameter sign stays in front. Do not type %%c800: that replaces the measurement with fixed text. As shown in radius dimensions in AutoCAD, a dimension typed over keeps its old number after the geometry changes.
Degree symbol in AutoCAD and plus minus symbol in AutoCAD
The two codes that travel with %%c behave more simply, because all three fonts have real glyphs for them:
| Code | Arial | romans.shx | txt.shx | In an Arial PDF |
|---|---|---|---|---|
%%d45 | °45 | °45 | °45, a small diamond-shaped mark | °45, character U+00B0 |
%%p5 | ±5 | ±5 | ±5 | ±5, character U+00B1 |
So the degree symbol in AutoCAD and the plus minus symbol in AutoCAD never have the two-shape problem of the diameter. The only visible difference is the degree mark of txt.shx, which is drawn as a small diamond rather than a round circle.
In a PDF, Arial text keeps both as real characters that can be searched. SHX text keeps them only in reader comments: for TEXT the comment holds the raw codes %%d45 and %%p5, while for MTEXT it holds the finished characters °45 and ±5.
Place the code where the symbol belongs. %%d goes after the number for an angle (30%%d), %%p goes before it for a tolerance or level (%%p0.000).
Other control codes in the family
Besides %%c, %%d and %%p, the same double-percent family includes:
| Type | Shows |
|---|---|
%%uUNDERLINED%%u | Underlined text |
%%oOVERLINED | Overlined text |
%%21616 | Ø16, where 216 is the character number of Ø |
%%24816 | ø16, the lower-case ø |
%%nnn calls a character by number. But %%216 is the letter Ø, not the diameter sign: in romans.shx it draws the same tall letter as a pasted Ø, so do not use it instead of %%c.
The diameter symbol after exporting to PDF
Drawing sets usually go out as PDF, and recipients often search for "Ø16" to count bars. The result depends on the font:
| Typed as | Font | Found in the PDF |
|---|---|---|
%%c16 in TEXT | Arial | Ø16 in the page content |
%%c16 in TEXT | SHX | Only a comment holding the raw string %%c16 |
%%c16 in MTEXT | SHX | A comment that has lost the symbol, just 16 |
\U+2205 16 | SHX | A comment that has lost the symbol, just 16 |
Only TrueType text gives a PDF where the diameter is really searchable. If recipients count bars by searching the PDF, use an Arial-based style for every rebar note, or send the DWG alongside the PDF so they can count from the drawing itself. SHX text is strokes; the original text survives only in a reader comment, and the diameter sign is dropped in two of the three cases. SHX text in PDFs is covered in saving AutoCAD as PDF.
Three things often repeated that are not true
| Often repeated | What holds on the 2027 release |
|---|---|
%%c must be lower case | %%C gives exactly the same result |
| The letter Ø and the diameter sign are the same | In SHX fonts the letter Ø looks quite different from the diameter sign |
%%c always draws the same shape | Arial draws the letter Ø; SHX fonts draw a neat diameter sign |
Frequently asked questions
How do I type the diameter symbol in AutoCAD?
Type %%c right before the number: %%c16 shows Ø16. It works in both TEXT and MTEXT, in either case.
Why does my diameter symbol look different from a colleague's?
You use different fonts: Arial draws the letter Ø, SHX fonts draw the diameter sign. Or one of you pasted a letter Ø instead of typing %%c.
How do I type the degree and plus/minus symbols?
%%d for degrees and %%p for ±, e.g. %%p0.000 for level ±0.000 and 30%%d for 30°. Both draw correctly in Arial and in SHX fonts.
How does \U+2205 differ from %%c?
In SHX fonts they draw the same shape. They differ in storage: %%c is kept as the control code, \U+2205 as the Unicode code.
Why can't I find Ø16 in the PDF?
Text in SHX fonts is drawn as strokes. Switch the text style to Arial and Ø16 becomes searchable in the page content. With SHX text, the PDF only keeps the original string in reader comments, and for MTEXT even that loses the symbol.
What code does a diameter dimension use?
DIMDIAMETER inserts \U+2205 in front of the value by itself; there is nothing extra to type for it.