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U+03C4 · Greek and Coptic

Greek Small Letter Tau τ

The lowercase tau τ is the nineteenth letter of the Greek alphabet. Engineers and physicists use it for torque, shear stress, and time constants, such as the RC time constant of a circuit. Some mathematicians use τ for the full-circle constant 2π, about 6.28318, and particle physicists use it for the tau lepton.

WindowsAlt 231
UnicodeU+03C4
HTMLτ
τU+03C4

Character codes

Unicode code pointU+03C4
Decimal964
HTML named entityτ
HTML (hex)τ
HTML (decimal)τ
CSS\03C4
JavaScript\u03C4
Python\u03C4
UTF-8 bytesCF 84
UTF-1603C4
URL-encoded%CF%84

Character details

Official nameGREEK SMALL LETTER TAU
Unicode blockGreek and Coptic
General categoryLowercase Letter (Ll)
SymbolHero categoryGreek Letters
UppercaseΤ Greek Capital Letter Tau
EmojiNo

How to type τ

Windows

  • Hold Alt and type 231 on the numeric keypad (Num Lock on), then release Alt. Alt 231 uses the code page 437.
  • In Microsoft Word or Outlook: type 03C4 then press Alt + X.
  • Open Character Map (search “Character Map” in Start), tick “Advanced view”, search for “greek small letter tau”, then Select and Copy.

Mac

  • Press Control + Command + Space to open the Character Viewer, search “greek small letter tau”, and double-click the result.
  • With the Unicode Hex Input keyboard enabled (System Settings → Keyboard → Input Sources), hold Option and type 03C4.

iPhone & Android

  • Tap Copy at the top of this page, then long-press where you want it and choose Paste.

Docs & web

  • Google Docs: Insert → Special characters, then search “greek small letter tau” or enter U+03C4.
  • HTML: τ or τ
  • Excel / Google Sheets: =UNICHAR(964)

Examples

  • τ = r × F
  • RC circuit: τ = RC
  • τ = 2π ≈ 6.28318
  • Shear stress τ = 40 MPa

Good to know

Tip: In some fonts τ looks like a small Latin t, so choose a font with clear Greek glyphs for technical documents.

Display: the character itself is always the same code point, but its shape comes from the font on the device showing it. If you see an empty box, the font lacks this glyph—the text is still correct.

Guides

Greek Alphabet Symbols: Every Letter to Copy and Paste

Similar greek letters

Greek Capital Letter Phi
Omega (Capital)
Alpha (α)
Beta (β)
Gamma (γ)
Delta (δ)
Epsilon (ε)
Theta (θ)
Lambda (λ)
Mu (μ)
Pi Symbol
Sigma (σ)
Phi (φ)
Omega (ω)
Greek Capital Letter Heta
Greek Small Letter Heta
Greek Capital Letter Archaic Sampi
Greek Small Letter Archaic Sampi
Greek Numeral Sign
Greek Capital Letter Pamphylian Digamma
Greek Small Letter Pamphylian Digamma
Greek Ypogegrammeni
Greek Small Reversed Lunate Sigma Symbol
Greek Small Dotted Lunate Sigma Symbol

See all 333 greek letters →

Questions

What is the Unicode for τ?

It is U+03C4 (GREEK SMALL LETTER TAU), decimal 964.

Is there a Windows Alt code for it?

Yes: Alt 231 on the numeric keypad.

How do I type it on a Mac?

There is no built-in Option shortcut. Use the Character Viewer (Control + Command + Space) and search “greek small letter tau”, or copy it from this page.

What is the HTML code?

Use the named entity τ or the numeric reference τ.