Phi (/ faɪ /; [1] uppercase Φ, lowercase φ or ϕ; Ancient Greek: ϕεῖ pheî [pʰéî̯]; Modern Greek: φι fi [fi]) is the twenty-first letter of the Greek alphabet. In Archaic and Classical Greek (c. 9th to 4th century BC), it represented an aspirated voiceless bilabial plosive ([pʰ]), which was the origin of its usual romanization as ph .

Greek alphabet letters and symbols. Greek letters pronunciation.

Phi is the 21st letter of the Greek alphabet. It is used in various contexts, including mathematics, science, and engineering, where it often represents the golden ratio (φ). Uppercase Phi - Φ; Lowercase Phi - φ

Phi (uppercase/lowercase Φ φ), is the 21st letter of the Greek alphabet, used to represent the "ph" sound in Ancient Greek. This sound changed to "f" some time in the 1st century AD, and in Modern Greek the letter denotes the "f" sound.

Click to copy the phi symbol (Φ φ ϕ 𝛟 𝜑 𝜙 𝝋 𝝓 𝞓 𝞿 𝟇 Ⲫ ⲫ) and paste it on Instagram, WhatsApp, TikTok, YouTube, Facebook, LinkedIn, Snapchat, Reddit, Discord, Telegram, X (formerly Twitter), Pinterest, Threads, and more. On macOS: Press Control + Command + Space or Fn + E to open the emoji picker.

The Greek letter φ (phi) is used in geometry as a constant to represent the golden ratio.

Phi (uppercase Φ, lowercase φ) is the 21st letter of the Modern Greek alphabet. In the Greek number system, it was taken as the symbol of 500. In math, the lowercase letter phi (φ) is used to indicate the golden ratio.