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Greek alphabet | |||||
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Αα Alpha | Νν Nu | ||||
Ββ Beta | Ξξ Xi | ||||
Γγ Gamma | Οο Omicron | ||||
Δδ Delta | Ππ Pi | ||||
Εε Epsilon | Ρρ Rho | ||||
Ζζ Zeta | Σσς Sigma | ||||
Ηη Eta | Ττ Tau | ||||
Θθ Theta | Υυ Upsilon | ||||
Ιι Iota | Φφ Phi | ||||
Κκ Kappa | Χχ Chi | ||||
Λλ Lambda | Ψψ Psi | ||||
Μμ Mu | Ωω Omega | ||||
Obsolete letters | |||||
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Other characters | |||||
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Greek diacritics |
Phi (uppercase Φ, lowercase φ or ϕ), pronounced [fī] in modern Greek and as [faɪ] in English, is the 21st letter of the Greek alphabet. In modern Greek, it represents [f], a voiceless labiodental fricative. In Ancient Greek it represented [pʰ], an aspirated voiceless bilabial plosive (from which English ultimately inherits the spelling "ph" in words derived from Greek). In the system of Greek numerals it has a value of 500 (φʹ) or 500,000 (͵φ). The Cyrillic letter Ef (Ф, ф) arose from phi.
The lower-case letter (or often its variant,
) is used as a symbol for:
The upper-case letter Φ is used as a symbol for:
The diameter symbol in engineering, ⌀, is often incorrectly referred to as "phi". This symbol is used to indicate the diameter of a circular section, for example ⌀14 means the diameter of the circle is 14 units.
In Unicode, there are multiple forms of the phi letter:
In HTML/XHTML, the upper and lower case phi character entity references are Φ (Φ) and φ (φ) respectively.
In LaTeX, the math symbols are \Phi (), \phi (
), and \varphi (
).
In some browsers (e.g. Internet Explorer 6), the shapes of the U+03C6 GREEK SMALL LETTER PHI (which should be viewed as a curl) and U+03D5 GREEK PHI SYMBOL (which should be viewed as a circle crossed by a slash) are exchanged. Compare these samples to check your browser:
Character | Name | Correct appearance | Your browser |
---|---|---|---|
U+03C6 | GREEK SMALL LETTER PHI | ![]() |
φ |
U+03D5 | GREEK PHI SYMBOL | ![]() |
ϕ |