Phi Symbol (φ Φ): How to Type It & the Golden Ratio

Short answer: Tap a phi below to copy it. To type it: on Windows, Alt + 966 = φ, Alt + 934 = Φ (numeric keypad); on Mac, open the Character Viewer (Control + Command + Space) and search “phi,” or add the Greek input source; in Word, type 03C6 then Alt + X; in HTML use φ / Φ; in LaTeX use \phi / \Phi (and \varphi for the other shape).

Phi is the 21st Greek letter — see the whole set in the Greek alphabet guide, or get any letter’s codes from the Alt Code Finder.

Phi (Φ uppercase, φ lowercase) is the 21st letter of the Greek alphabet, and it’s most famous as the symbol for the golden ratio, φ ≈ 1.618. It also shows up for magnetic flux, phase angles and more — and it comes in two lowercase shapes that trip people up.

φ vs ϕ — the two phi shapes

Lowercase phi exists as two separate Unicode characters:

φ — Greek small letter phi (U+03C6): the letter used in ordinary Greek text, usually drawn in the “loopy” / open form.
ϕ — Greek phi symbol (U+03D5): intended as the mathematical symbol, usually drawn in the “straight” / closed form (a circle with a vertical line through it).

The two phi shapes — the loopy Greek letter and the straight math symbol

Here’s the catch worth knowing: Unicode swapped the representative glyphs of these two in 2002, and many older fonts still show them reversed — so which shape you actually see depends on the font. For plain text and Greek, use φ (U+03C6); if a formula or style specifically wants the straight math symbol, use ϕ (U+03D5). In LaTeX, \phi and \varphi give the two different shapes, so check the rendered output when the exact form matters.

Quick reference

Symbol	Name	Windows	Mac	HTML	LaTeX	Unicode
φ	Greek small phi	Alt + 966	Viewer / Greek input	`φ`	`\phi`	U+03C6
Φ	Greek capital phi	Alt + 934	Viewer / Greek input	`Φ`	`\Phi`	U+03A6
ϕ	Phi symbol (variant)	Alt + 981	Viewer	`ϕ`	`\varphi`	U+03D5

Type phi on Windows

Alt codes: hold Alt, type on the numeric keypad (Num Lock on): Alt + 966 → φ, Alt + 934 → Φ, Alt + 981 → ϕ. Use a Unicode-aware app (Word, browsers, email).
Word: type 03C6 and press Alt + X for φ, 03A6 + Alt + X for Φ, or 03D5 + Alt + X for ϕ. In an equation (Alt + =), type \phi, \Phi or \varphi then Space.
Lots of Greek: add the Greek keyboard and switch with Windows + Space.

Type phi on Mac

Macs have no direct Option shortcut for phi:

Character Viewer: press Control + Command + Space, search “phi,” and double-click φ, Φ or ϕ.
Greek input source: add it under System Settings → Keyboard → Input Sources for regular Greek typing, or use Unicode Hex Input (Option + 03C6).

Phi in Word

The 03C6 + Alt + X method is quickest; otherwise Insert → Symbol → (Greek and Coptic), or an equation (Alt + =) with \phi / \Phi. For the golden ratio, you might write φ = (1 + √5) / 2.

Phi in HTML & LaTeX

HTML: φ → φ, Φ → Φ, and ϕ (or ϕ) → ϕ; numeric fallbacks φ / Φ / ϕ work too.
LaTeX (math mode): \Phi for Φ; for lowercase, \phi and \varphi produce the two different shapes (one more closed/straight, one more open/curly). Which looks like which can depend on the font and math package, so verify the output for published work.

Type phi on Linux & phone

Linux: Ctrl + Shift + U, then 03c6 (φ) or 03a6 (Φ), then Enter.
Phone: add a Greek keyboard (iPhone: Settings → General → Keyboard; Android: Gboard languages) and switch with the globe key, or copy φ/Φ from the tool above.

What phi means

The golden ratio (φ) — φ = (1 + √5) / 2 ≈ 1.6180339887, the proportion found throughout art, architecture, design and nature (and tied to the Fibonacci sequence). The related golden angle is about 137.5°.
Magnetic flux (Φ) — uppercase phi in physics, measured in webers, central to Faraday’s law.
Electric potential / work function — φ or Φ.
Phase angle (φ) — in AC circuits and wave physics.
Euler’s totient function φ(n) — in number theory, counting integers coprime to n.
Latitude (φ) — in geography and geodesy; and the azimuthal angle in spherical coordinates.

Troubleshooting

Problem	Fix
Alt + 966 gives the wrong character	Use the numeric keypad with Num Lock on, in a Unicode-aware app.
φ shows as a box ▯	Font lacks the glyph — switch to Segoe UI, Cambria Math or STIX Two Math. See symbol showing as a box.
φ looks straight in one app, loopy in another	Normal — the two representative glyphs were swapped in 2002, so appearance is font-dependent. Use the exact code point you intend.
I confused φ with ∅	φ is the Greek letter; ∅ (U+2205) is the empty-set / null sign — a different character. Watch also for ø (o-slash) and ⌀ (diameter).
Pasted phi changed shape	Apply a math-friendly font (Cambria Math, STIX Two Math, Latin Modern Math).

Recap

Windows → Alt + 966 (φ) / Alt + 934 (Φ); Word: 03C6 + Alt + X.
Mac → Character Viewer (Control + Command + Space) — no Option shortcut.
Web → φ / Φ. LaTeX → \phi / \Phi, \varphi for the other shape.
Golden ratio → φ ≈ 1.618; either φ or ϕ is used for it.

Frequently asked questions

What does the phi symbol mean?

Phi is the 21st letter of the Greek alphabet, written Φ (uppercase) and φ (lowercase). It’s best known as the symbol for the golden ratio, φ ≈ 1.618, and it also represents magnetic flux (Φ), phase angles, Euler’s totient function φ(n) and latitude, among other quantities.

What’s the difference between φ and ϕ?

They’re two Unicode characters for the same letter: φ (U+03C6) is the Greek small letter phi used in ordinary text, usually drawn in the loopy form, and ϕ (U+03D5) is the phi symbol used in maths, usually drawn straight. Unicode swapped their representative glyphs in 2002, so the exact shape depends on the font — use φ for text and ϕ when a formula specifically calls for the straight symbol.

How do I type phi on Windows?

Hold Alt and type 966 on the numeric keypad for φ, or 934 for Φ, in a Unicode-aware app. In Word, you can also type 03C6 (or 03A6) and press Alt + X, or use \phi in an equation. For lots of Greek, add the Greek keyboard layout.

How do I type phi on a Mac?

Macs have no direct Option shortcut for phi. Open the Character Viewer with Control + Command + Space, search “phi,” and insert φ, Φ or ϕ, or add the Greek input source for regular Greek typing.

What is the golden ratio symbol?

The golden ratio is written with the Greek letter phi, φ, and equals (1 + √5) / 2, approximately 1.618. You can type it with Alt + 966 on Windows, φ in HTML, or \phi in LaTeX. Both the loopy φ and the straight ϕ are used for it in practice.

What’s the difference between φ and ∅?

φ is the Greek letter phi, while ∅ (U+2205) is the empty-set or null-set symbol from mathematics — a different character despite the resemblance. It’s also distinct from ø (the Danish/Norwegian o-slash) and ⌀ (the diameter sign), which are sometimes confused with phi.

Written by Igor R.. Tested on Windows 11, macOS, Word and LaTeX. Symbol code points follow the Unicode Standard. Last updated July 2026.