Free Mechanical Drawing Reference
Mechanical engineering symbols to copy and paste into PDF redlines
Copy diameter, plus-minus, degree, counterbore, countersink, depth, drafting, and GD&T symbols as real text for your next mechanical drawing review.
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Paste clean symbols into a PDF redline note
When a drawing review needs a quick note, hunting through a character map slows down a simple redline. The tables below keep common mechanical engineering symbols in one place. Copy a single character or grab a ready-made callout and adjust the values.
These are Unicode text characters, so font coverage matters. If a symbol appears as an empty square after pasting, try a different font or use a native mechanical annotation tool.
Copy and paste reference
Mechanical engineering symbol list
Each button copies the actual character shown in the table. The example column shows one way the symbol can appear in a plain-text review note.
Common dimension and tolerance symbols
Start here for the symbols that appear most often in drawing review notes, dimension changes, and tolerance redlines.
| Symbol | Name | Use in a redline | Example | Copy |
|---|---|---|---|---|
| ⌀ | DiameterU+2300 | Place before a value for a diameter dimension. This is the diameter sign, not a slashed letter O. | ⌀12.00 ±0.05 | |
| ± | Plus-minusU+00B1 | Use for a bilateral tolerance or a plus-minus variation. | 12.00 ±0.05 | |
| ° | DegreeU+00B0 | Use after an angular value or temperature value when the context is clear. | 45° | |
| × | Multiplication signU+00D7 | Useful for hole quantities, patterns, and dimensions written as a product. It is clearer than a lowercase x. | 4 × ⌀6 THRU | |
| □ | SquareU+25A1 | Common plain-text prefix for a square feature or square dimension. | □12 | |
| ℄ | Centre lineU+2104 | Use when a redline note needs a centerline reference. | DIM TO ℄ | |
| ″ | Double primeU+2033 | A typographic inches mark for plain-text dimensions when inch units are needed. | 0.250″ | |
| µ | Micro signU+00B5 | Useful in micrometre units for surface, inspection, or manufacturing notes. | 3.2 µm |
Hole feature symbols
These copyable characters are especially handy when marking up drilled, counterbored, and countersunk hole callouts.
| Symbol | Name | Use in a redline | Example | Copy |
|---|---|---|---|---|
| ⌴ | CounterboreU+2334 | Use before the counterbore diameter in a plain-text hole callout. | ⌴ ⌀10 ↧ 4 | |
| ⌵ | CountersinkU+2335 | Use before the countersink diameter and included angle in a plain-text hole callout. | ⌵ ⌀12 × 90° | |
| ↧ | DepthU+21A7 | A common plain-text depth mark. Its Unicode name is DOWNWARDS ARROW FROM BAR. | ↧ 8 |
Drafting symbols
Unicode includes several technical drawing characters that can be pasted into concise drawing review notes.
| Symbol | Name | Use in a redline | Example | Copy |
|---|---|---|---|---|
| ∠ | AngleU+2220 | Useful before an angular value when a note needs an explicit angle mark. | ∠ 30° | |
| ⌱ | Dimension originU+2331 | Use when identifying a dimension origin in a drafting note. | ⌱ | |
| ⌲ | Conical taperU+2332 | Use for a conical taper reference in a plain-text note. | ⌲ 1:10 | |
| ⌳ | SlopeU+2333 | Use for a slope reference in a plain-text note. | ⌳ 1:20 | |
| Δ | DeltaU+0394 | Useful as a change marker in review notes when your team's redline convention uses delta callouts. | Δ NOTE 4 | |
| ≈ | Approximately equalU+2248 | Useful for an approximate value in an informal review note. | ≈ 25 mm | |
| ≤ | Less than or equalU+2264 | Useful for an upper limit in a review note. | BURR ≤ 0.05 | |
| ≥ | Greater than or equalU+2265 | Useful for a lower limit in a review note. | HARDNESS ≥ 40 HRC |
Copyable GD&T symbols for review notes
These Unicode characters are useful in short notes and search terms. For a controlled feature control frame, use a proper GD&T annotation tool.
| Symbol | Name | Use in a redline | Example | Copy |
|---|---|---|---|---|
| ⌖ | Position indicatorU+2316 | Useful as a plain-text position reference in a drawing review note. | ⌖ ⌀0.10 | A | B | C | |
| ⏤ | StraightnessU+23E4 | A copyable straightness character for concise GD&T review notes. | ⏤ 0.05 | |
| ⏥ | FlatnessU+23E5 | A copyable flatness character for concise GD&T review notes. | ⏥ 0.05 | |
| ⌭ | CylindricityU+232D | A copyable cylindricity character for concise GD&T review notes. | ⌭ 0.05 | |
| ⌮ | All around profileU+232E | A copyable all-around profile character for concise GD&T review notes. | ⌮ | |
| ⌯ | SymmetryU+232F | A copyable symmetry character for legacy drawing review contexts. | ⌯ 0.10 | |
| ⌰ | Total runoutU+2330 | A copyable total runout character for concise GD&T review notes. | ⌰ 0.05 | A |
Ready-made snippets
Copy a mechanical redline callout and edit the values
These snippets are convenient starting points for informal review notes. Match the final redline to your drawing standard and your team's review conventions.
Diameter with tolerance
⌀12.00 ±0.05Counterbore hole
4 × ⌀6 THRU, ⌴ ⌀10 ↧ 4Countersink hole
4 × ⌀6 THRU, ⌵ ⌀12 × 90°Tapped hole depth
M6 × 1.0 ↧ 12Square feature
□12 ±0.10Plain-text position review note
VERIFY ⌖ ⌀0.10 | A | B | CDiameter symbol note
Use ⌀ for diameter, not the letter Ø
The proper Unicode diameter sign is ⌀ at U+2300. The character Ø is a letter. They can look similar in some fonts, but they are not the same text character.
That distinction matters when teammates search notes, reuse a redline, or move text between software tools. Use the copy button here to keep the actual diameter sign intact.
When text is not enough
Use copyable symbols for quick notes and native tools for formal redlines
Plain text is great for short comments: add a missing diameter, question a countersink angle, or note a depth change. More structured annotations deserve proper tools. A GD&T feature control frame, BOM balloon, flag note, weld symbol, or carefully placed leader should stay legible and intentional on the print.
PDF Engineer is built for that mechanical drawing review workflow. You can keep the speed of a PDF markup tool without assembling every engineering annotation from generic text boxes and shapes.
FAQ
Mechanical symbol copy and paste questions
How do I copy and paste a diameter symbol?
Use the diameter sign ⌀. Select the symbol or use the Copy button on this page, then paste it into a text note in your PDF redline tool. The Unicode diameter sign is U+2300.
What is the difference between the diameter symbol ⌀ and Ø?
The diameter sign is ⌀ (U+2300). The visually similar Ø character is a letter used in several languages. Use the diameter sign for mechanical drawing redlines when your PDF tool and font support it.
How do I type a counterbore or countersink symbol?
Copy ⌴ for counterbore and ⌵ for countersink from this page. Both are Unicode technical characters, so you can paste them into a PDF text annotation when the selected font supports them.
Why does a pasted mechanical symbol appear as an empty box?
The font used by your PDF text tool may not contain that Unicode character. Try another font or use a mechanical PDF redline tool with native annotation support for the mark you need.
Can plain-text symbols replace a GD&T feature control frame?
No. Plain-text symbols are convenient for quick review notes and search terms, but a formal GD&T redline should use a proper feature control frame tool so compartments, modifiers, and datum references stay clear.
Sources
Official Unicode reference charts
Unicode charts define the text characters on this page. Drawing standards and company practices still govern how a released engineering drawing should communicate requirements.
- Unicode Miscellaneous Technical chart
Official Unicode chart containing the diameter sign, position indicator, cylindricity, total runout, dimension origin, taper, slope, counterbore, countersink, straightness, and flatness characters.
- Unicode Letterlike Symbols chart
Official Unicode chart containing the centre line symbol.
- Unicode General Punctuation chart
Official Unicode chart containing the double prime character.
- Unicode Mathematical Operators chart
Official Unicode chart containing angle, approximately equal, less-than-or-equal, and greater-than-or-equal characters.