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Theta Symbol (θ)
Theta (θ) is the Greek letter maths uses for angles more than any other — if a problem has an unknown angle, it is probably θ.
Theta Symbol codes
| Code | Value |
|---|---|
| Unicode code point | U+03B8 |
| Unicode name | Greek Small Letter Theta |
| HTML named entity | θ |
| HTML decimal | θ |
| HTML hex | θ |
| CSS content code | \3B8 |
| JavaScript / JSON | \u03B8 |
| Windows Alt code | No standard Alt code — copy it from the card above |
| LaTeX | \theta |
Theta Symbol variants (4)
4 related glyphs — click any tile to copy it. Tiles with a page open that symbol's own page.
Meaning & usage
θ is the eighth letter of the Greek alphabet and the world's default name for an angle: trigonometry problems, physics diagrams and engineering formulas all reach for θ first. In economics it marks option price sensitivity over time ('theta decay'), and in neuroscience theta waves are a brain rhythm linked to memory. The capital Θ looks like an O with a bar; the lowercase ϑ variant is a curly form some textbooks prefer.
Examples in use
- sin θ = opposite / hypotenuse
- Find θ when the ladder leans at 5 m
- Theta waves rise during meditation
How to type the theta symbol
Windows
There is no Alt code or direct key for θ. In Microsoft Word, type 03B8 and press Alt+X to convert it. Everywhere else, click the Copy button at the top of this page and paste it (Ctrl+V) — that always works.
Mac
There is no Option-key shortcut for θ on a Mac. Open the Character Viewer with Control+Command+Space, search for "Theta Symbol", and double-click to insert — or copy it from this page.
iPhone & Android
Most phone keyboards have no built-in key for θ. Open this page on your phone, tap Copy, then paste it into your message or bio. (On Android, Gboard's emoji search finds some symbols by name.)
Linux
Press Ctrl+Shift+U, type 03b8 and press Enter (works in most GTK apps and terminals with IBus). Or copy it from this page.
Frequently asked questions
How do I type θ on a keyboard?
There is no standard Alt code. Copy θ from this page; in Word, type 03B8 then press Alt+X.
Why is θ used for angles?
It is a long-standing convention — Greek letters are maths' spare alphabet, and theta became the standard placeholder for an unknown or general angle.
Why does θ sometimes show as a box or question mark?
The box (called tofu) means the device or font viewing it has no drawing for U+03B8 (Greek Small Letter Theta). The character itself is fine — try a different font or a newer device, or use one of the variants on this page.
Is the Theta Symbol free to use?
Yes. θ is a standard Unicode text character published in the Unicode Character Database. You may use it in personal and commercial documents, designs and products without permission or payment.
Related symbols
More in Greek Letters · All symbols
Data: Unicode Character Database · Page updated 2026-11-13