Engineering Drawing Symbols & How to Type Them

Engineering drawings are, by themselves, difficult to parse and understand for anyone without a background in what the different symbols mean.

However, this is nothing compared to actually trying to produce one. While it’s great knowing how to read an engineering drawing and what all the different symbols mean, knowing how to reproduce them is a different skill set entirely. For many, every time they need to note the diameter of a bore or the thread pitch of a precision screw, they use a search engine to find the symbol, then copy and paste it into the sheet they’re working on.

While this is functional, it’s far from ideal and won’t teach you how to produce the symbols yourself, which is often just a matter of pressing a few keys on your keyboard to pull up any symbol you require. This guide shows you how to produce all of the essential, commonly used technical drawing symbols you’ll need to create your own engineering drawings, as well as providing breakdowns for both Windows and Mac users.

And, if at the end of this guide you still prefer to copy and paste, be sure to bookmark this article so you have all the symbols you need in one place.

 

Contents:

• Every Typing Method, Explained

• The Most Essential Engineering Drawing Symbols

• Engineering Drawing Keyboard Symbols: Quick-reference Shortcut Tables

• Technical Drawing Symbols Most Guides Ignore

• Set Up Your Own Shortcuts

• Key Takeaways

• FAQs

Every Typing Method, Explained

While the purpose of this article may sound simple, there are a few things to remember. For a start, while most standard computer keyboards come with commonly used symbols mapped to different keys, none of the symbols in this guide have standard key mappings. After all, if they did, there’d be no need for us to make this guide. So the keyboard shortcuts listed in this guide to produce them look a little more complicated than something like Option+3 to produce a #. They instead consist of multiple keys, typed in sequence, to produce the required symbol.

The example above also brings up another important note: different operating systems. The shortcut above is for a Mac, so won’t be of use to a Windows user, who might stare blankly at their keyboard and wonder which is the option key. A shortcut written for one operating system won’t work on the other, so it’s important to get them right.

For this guide, we’ve broken out both Windows and Mac instructions to keep things clear and easier to both find and understand. There are a few quirks to how to input the required codes to get the symbol you want, which you’ll find outlined below. Rather than repeat these for every set of instructions or symbol, check below and find the instructions that match your set-up, then apply those to the directions given for the symbols you find in this article:

• Windows Alt codes (fastest, if you have a keypad): hold Alt, type the number on the numeric keypad with Num Lock on, then let go. The symbol appears where your cursor is. It has to be the numpad on the right, not the row of numbers along the top.

• Windows without a numeric keypad: plenty of laptops drop the keypad, which stops Alt codes from working. Two easy ways around it: press the Windows key and full stop together for the emoji and symbol panel, then open the Symbols tab, or search "Character Map" from the Start menu and copy what you need.

• Windows Unicode in Word (Alt+X): for the symbols with no Alt code, Word has a tidy trick. Type the four-character code, for example 2300, then press Alt and X together and it becomes the symbol. Fumble it? Press Alt+X again to switch it back.

• Mac Option keys (fastest on a Mac): hold Option, or Option and Shift together, and press the key shown. Nothing to switch on first, and no keypad needed.

• Mac Character Viewer: for anything without a shortcut, open the Character Viewer with Control, Command and Space, search the symbol name, then double-click to drop it in.

• Any application, the reliable fallback: in Word, Excel or PowerPoint, go to Insert then Symbol; in Google Docs, Insert then Special characters. Search the name and click, and your recent picks stay handy for next time.

• AutoCAD: on a drawing, you rarely need an Alt code at all. Type a control code straight into your text and AutoCAD swaps it for the symbol: %%c for diameter, %%d for degree and %%p for plus or minus.

A Note on UK Drawing Conventions

In the UK, most engineering drawings follow BS 8888, which lines up with the International Organisation for Standardisation (ISO) system, while a lot of US work uses ASME Y14.5. The symbols are largely the same across all of them; it is the finer points of tolerancing and presentation that differ, so it is always worth matching your drawing to whatever standard your project or customer asks for. 

If you want the full picture on standards, our guide to reading engineering drawings goes deeper. Throughout this one we have kept to metric-first examples and British spelling, as most UK work does.

The Most Essential Engineering Drawing Symbols

Some symbols you will reach for constantly. Others you might use once a year. This section covers the everyday workhorses, the handful that turn up on almost every drawing, so they’re quick to find when you’re mid-flow. The rarer, more specialist symbols come later in the guide.

The diameter symbol (⌀)

The diameter symbol (⌀) tells anyone reading a drawing that a dimension applies to a full circle or cylinder, not the radius. It goes before the value, so a 25 millimetre hole is written ⌀25, and it’s often paired with a tolerance, as in ⌀25 ±0.1 mm. Note that because both measurements are in mm, it’s not necessary to write it as ⌀25 mm ±0.1 mm.

Here is where most people go wrong. Four characters look almost identical and only one is correct:

• ⌀ is the true diameter sign (Unicode U+2300), a circle crossed by a line that extends beyond it.

• Ø is the Scandinavian capital letter O with a stroke (U+00D8). It is the everyday stand-in because it is far easier to type, and it reads fine in most contexts, but it is technically a letter, not a symbol.

• ∅ is the mathematical empty set (U+2205).

• φ is the Greek letter phi, sometimes mistaken for diameter but meaning something else entirely.

So which do you use? On a formal drawing, always ⌀. For a quick email or a note where you are not sure how it will render, the slashed O (Ø) will do the job and nobody will misread you. Just keep the two straight for anything that matters.

• Windows: for the true sign, type 2300 then press Alt+X in Word. For the Ø stand-in, hold Alt and type 0216 on the numeric keypad. The diameter symbol alt code you will often see quoted, Alt+8960, works in Word and other Office apps but not everywhere, so 2300 then Alt+X is the safer bet.

• Mac: the slashed O is Option+Shift+O. The true diameter sign has no default shortcut, so open the Character Viewer with Control+Command+Space and search "diameter".

• AutoCAD: type %%c and it becomes ⌀ automatically, which is why most engineers never touch an Alt code on a drawing.

It’s worth knowing the radius symbol too, since the two are so easily confused. Radius is written as a plain capital R before the value, as in R12, and needs no special character at all. The catch is that R12 and ⌀12 are not the same size: a radius runs from the centre of a circle to its edge, so R12 describes a circle 24 mm across, while ⌀12 describes one just 12 mm across. Easy to mistake, but reading them wrong can mean something comes out either twice the size it’s meant to, or half.

 

The degree symbol (°)

You’ll see the degree symbol called the degrees symbol or the sign for degrees. Whichever you use, that one small superscript circle does two jobs: it marks an angle (90°) and a temperature (20°C). The context tells the reader which, so the same glyph serves both without ambiguity.

• Windows: Alt+0176 on the numeric keypad.

• Mac: Option+Shift+8.

• AutoCAD: the control code %%d.

A quick note on style, since it trips people up. Repeat the symbol across a range rather than sharing it, so write 60° to 90°, not 60 to 90°.

 

Plus or minus, and tolerance symbols (± and ∓)

The plus or minus symbol is the language of tolerance. It defines the acceptable band around a nominal size, so ⌀12 ±0.05 mm tells the machinist the hole may finish anywhere from 11.95 to 12.05 millimetres. Get the symbol wrong and you’ve inadvertently changed the specification.

There are two related glyphs. The plus or minus sign, ±, is the one you want almost every time. Its mirror, the minus or plus sign ∓, appears in paired equations to mean "take the opposite sign", but it’s rare on a drawing.

• Windows: Alt+0177 for ±.

• Mac: Option+Shift+= for ±.

• AutoCAD: the control code %%p.

On a laptop with no numeric keypad: this is the single most common frustration with tolerance symbols. On Windows, open the emoji and symbol panel with the Windows key plus full stop or use Character Map. On Mac, you can use the same Option+Shift+= shortcut.

 

Multiplication, division and comparison operators (× ÷ ≥ ≤ ≠)

These maths operators turn up throughout specifications, from a thread callout like M8 × 1.25 to a fit condition written with a comparison sign. They share the same problem in that the keyboard offers a hyphen and a forward slash, but not the proper characters.

For multiplication on a formal drawing, use × rather than the letter x. 

Windows: Alt+0215

Mac: Use the Character Viewer, as there is no default shortcut. 

For division, use the divide symbol (÷), sometimes called the divide sign. 

Windows: Alt+0247 

Mac: Option+/ 

The comparison operators, greater than or equal to (≥), less than or equal to (≤) and not equal (≠), define limits and fits. 

Windows: The most reliable route is to use Word: type 2265, 2264 or 2260 and press Alt+X. 

Mac: Option+full stop (≥), Option+comma (≤) and Option+equals (≠).

 

Greek letters and unit symbols (Δ, µ and Ω)

Three Greek characters earn their keep on engineering drawings and in the notes that travel with them and all three sit just off the standard keyboard.

Delta (Δ) means a change in a quantity, so a change in temperature is written ΔT and a change in length ΔL. 

• Windows: type 0394 then Alt+X in Word. 

• Mac: Option+J gives the increment sign ∆, which looks all but identical and reads the same on a drawing (see the note under the tables on the two delta characters).

Micro (µ) is the prefix for one millionth, and you will meet it most often in microns (µm) and microfarads (µF). 

• Windows: Alt+0181. 

• Mac: Option+M.

Ohm (Ω) is the unit of electrical resistance, as in a 4.7 kΩ resistor. 

• Windows: Alt+234. 

• Mac: Option+Z.

Need a different Greek letter, like phi (φ), sigma (Σ) or theta (θ)? The same routes cover them all: the Character Map on Windows, the Character Viewer on Mac or Insert then Symbol in Office.

 

Squared, cubed and unit notation (² ³ √)

Area and volume call for superscripts, and they are among the symbols engineers look up most. A cross-section might be 50 mm², a volume 12 cm³. Superscript just means a smaller character lifted above the line of text, like the 2 in 10². The keyboard shortcut differs between programs. In Google Docs it is Control and full stop on Windows, or Command and full stop on a Mac; in Word it is Control, Shift and plus on Windows, or Command, Shift and plus on a Mac. If in doubt, the x² button in the toolbar always works. 

Squared (²): 

• Windows: Alt+0178. 

• Mac: No default shortcut, so use the Character Viewer, or format the 2 as superscript in your editor.

Cubed (³): 

• Windows: Alt+0179. 

• Mac: Use the Character Viewer, or a superscript 3.

Square root (√): 

• Windows: Alt+251. 

• Mac: Option+V.

One quick tip. The ² and ³ characters are cleaner than a manually superscripted number, because they copy and paste reliably between programs and never lose their formatting. Reach for the character on anything you might move around, and keep the superscript trick for a quick one-off.

Engineering Drawing Keyboard Symbols: Quick-reference Shortcut Tables

Here is the part to bookmark. Every key symbol in one place, split by platform so you aren’t wading through instructions meant for other operating systems. Find the symbol, read across to your setup and you’re done. If a shortcut ever looks cryptic, refer back to the methods section for an explanation of the notation.

Windows

Mac

Note: the Windows shortcut produces Δ (Greek capital delta) and the Mac one produces ∆ (the increment sign). They look almost identical and either is fine on a drawing, but they’re technically different characters.

Technical Drawing Symbols Most Guides Ignore

Beyond the everyday characters sit the drawing-specific symbols that the copy-and-paste websites rarely cover, yet they carry real meaning on a technical drawing. These are the symbols that separate an engineering reference from a generic one.

• Depth (↧, U+21A7): specifies how deep a hole or feature goes, replacing the word "deep".

• Counterbore (⌴, U+2334): a flat-bottomed enlarged hole to seat a bolt head flush.

• Countersink (⌵, U+2335): the angled recess for a countersunk fastener.

• Spherical diameter (S⌀): the prefix S with the diameter sign, marking a full spherical feature rather than a cylinder.

• Arc length (⌒, U+2312): shows a dimension is measured along a curve, not as a straight chord.

• Centreline (℄, U+2104): marks the centreline of a feature.

The reality is that most of these have no tidy keyboard shortcut. Your dependable options here are the Unicode value with Alt+X in Word (type the code shown, then press Alt+X), the Character Map on Windows, the Character Viewer on Mac or a dedicated Geometric Dimensioning and Tolerancing (GD&T) font in your Computer-Aided Design (CAD) package.

None of them are quick to type, so this is one of the few places where a copy and paste is genuinely the smart move. Bookmark this page, keep the codes above to hand and they stop being a problem.

Set Up Your Own Shortcuts

If you reach for the same few symbols every day, there is a faster way than looking up a code each time. Both Word and Mac let you teach the computer a short trigger of your own, so a handful of letters becomes the symbol you want, automatically, as you type. Spend two minutes setting it up once and the diameter sign, the degree symbol and the plus or minus sign are always a keystroke away.

Microsoft Word (and the rest of Office)

Word's AutoCorrect feature is built for exactly this. It already swaps "teh" for "the", for example. You can easily add your own entries the same way.

1. Insert the symbol you want once, using any method from the previous section, then select it and copy it.

2. Go to File, then Options, then Proofing, then AutoCorrect Options.

3. In the "Replace" box, type your trigger. In the "With" box, paste the symbol.

4. Click Add, then OK.

From then on, typing your trigger and pressing space turns it into the symbol. The entry works across Word, Outlook and the other Office applications, so a symbol you set up for drawings is also ready in your email.

 

Mac (system-wide)

Mac goes one better and offers text replacement across the whole system, not just one application. Set it up once and it works in Pages, Mail, Notes and most other apps.

1. Open System Settings, then Keyboard, then Text Replacements. (On older versions of macOS this lives under System Preferences, then Keyboard, then Text.)

2. Click the plus button.

3. In the "Replace" field, type your trigger. In the "With" field, enter the symbol.

4. Close the window to save.

Because these replacements sync through iCloud, the same triggers appear on your iPhone and iPad too, which is handy if you ever note a dimension on the move.

Choosing triggers that will not misfire

The one rule that matters: pick a trigger that never turns up in normal writing or the software will replace it when you least expect it. Set "dia" to convert to a diameter sign and every "dial" and "diagram" you type will misbehave. A clean, collision-free convention is to wrap a short code in brackets, so you might use:

• (dia) for ⌀

• (deg) for °

• (pm) for ±

• (ohm) for Ω

Keep the scheme consistent across your machines, test each entry once after you add it and you have a personal symbol set that follows you between documents. 

On a drawing in AutoCAD you need none of this, since the control codes %%c, %%d and %%p already do the same job, but for everything you write outside your CAD package a few well-chosen triggers save a surprising amount of time.

Key Takeaways:

An engineering drawing is only as clear as the symbols on it, so the gap between ⌀ and Ø or a tolerance written exactly as intended can be the difference between a part made right and a part made twice. 

Learn the methods once and every symbol becomes a keystroke, whether you’re working on Windows, on a Mac, in a document or straight into your CAD package. That same attention to precision runs through everything Accu does, which is why we supply over 750,000 precision components with a free downloadable CAD model for every standard part, so the feature on your drawing matches the component in your hand.

• The true diameter sign (⌀) and the Scandinavian slashed O (Ø) are not the same character. Ø is the quick everyday stand-in, but on a formal drawing only ⌀ is correct.

• There is a reliable route to every symbol on every platform: Windows Alt codes, Mac Option keys, the Alt+X trick in Word, Google Docs special characters and AutoCAD control codes.

• The symbols engineers reach for most, from depth and counterbore to countersink and spherical diameter, are the ones generic guides leave out. This one does not.

• Set up your own AutoCorrect or Text Replacement triggers once and you never hunt for a symbol again. Two minutes now saves hours later.

Further Reading:

• ISO Metric Thread Tolerance Tables

• How to Measure a Screw

• Free 3D CAD Model Downloads

FAQs:

Q: Is Ø the same as the diameter symbol ⌀? 

A: No. Ø is the Scandinavian letter O with a stroke (U+00D8), while ⌀ is the true diameter sign (U+2300). They look alike and are often used interchangeably, but for a formal drawing the correct character is ⌀.

Q: How do you type +/- on a laptop with no numeric keypad? 

A: On Windows, open the emoji and symbol panel with the Windows key plus full stop, or use Character Map. On Mac, press Option+Shift+=, which needs no keypad.

Q: What is the ± sign called? 

A: The plus or minus sign. On a drawing it defines a bilateral tolerance, the permitted band above and below a nominal size.

Q: How do you insert these symbols in AutoCAD? 

A: Use the control codes %%c for diameter, %%d for degree and %%p for plus or minus, or the \U+ Unicode form for other symbols in multiline text.

Q: Why does my symbol show as a box or a question mark? 

A: The font you are using does not include that character. Switch to a widely supported font such as Arial, or make sure the document is set to UTF-8 encoding.