Pronouncing Phi

Phee, Phi, Pho, Phum™ … or how do you say Φ?

The generally accepted pronunciation of phi is fi, like fly.

Most people know phi as “fi,” to rhyme with fly, as its pronounced in “Phi Beta Kappa.”  In Dan Brown’s best selling book “The Da Vinci Code,” however, phi is said to be pronounced fe, like fee.

The following is offered in response to the questions received on phi’s correct pronunciation:

Dictionairies either list fi as the only pronunciation for phi or, if both fi and fe are listed, as the primary pronunciation.  See listings at Merriam-Webster and

Leading authors on the subject of phi offered the following comments:

  • Two in the USA and UK confirmed that fi is the preferred pronunciation.
  • One noted that in the UK “phi” was always pronounced to rhyme with “pie” but that some Americans at conferences pronounced it “fee”.
  • Another noted that in Greek the letter PHI is indeed pronounced PHEE.  However, in Greek the letter we call PI is also pronounced PEE.  Consequently, depending on whether you want to adopt the Greek or American pronunciation you can pronounce it as PHEE or PHI.  In mathematical circles, the letter used for the Golden Ratio is normally TAU.

To complicate matters, when used in connection with fraternities and sororities, the usage varies as well and it is pronounced PHEE when it comes after a vowel, as in Alpha Phi.

My Greek phriend Tassos Spiliotopoulos offers the following:  The letters of the Greek alphabet are written as words and not as single letters, for example the first letter A is written AΛΦA and sounds like Alpha.  When it comes to letters like Π, Χ, Φ (written ΠI, ΧI and ΦI respectively), the misunderstanding comes from the pronunciation of the letter ‘I’ which in English rhymes with fly but in Greek is pronounced EE. The letter Φ is always pronounced PHEE in Greek, and it does not differ if followed by a vowel or a consonant.

So there you have it.  While a linguistic purist might opt for the original Greek fee, most mathematicians know phi as fi.  Either is correct, but if we want to be consistent with the common usage of pronouncing pi as pie, we would then pronounce phi as fi.

Or as the lyrics of the song say, “PotAto, potAHto, tomAto, tomAHto, let’s call the whole thing off.”


Many thanks to Dr. Mario Livio (author of The Golden Ratio), Dr. Ron Knott (author of Fibonacci Numbers and the Golden Section), Steve McIntosh (author of The Golden Mean and President of Now & Zen) and Dr. Eddy Levin (inventor of the Golden Mean Gauge) for their input, and to Geni Flowers for inspiring me to get the answer.


  1. danielle says

    Interesting information, but please don’t use “The Da Vinci Code” in anything resembling an academic discussion. Dan Brown is NOT a viable source reference. It is a fiction novel written for entertainment only, and is a historical and scientific farce. The use of it in an academic topic lowers the credibility of the topic.

  2. Al says

    Seeing as it is a Greek letter, I think it would be nice if people would pronounce the letter “pee” as it is supposed to be pronounced. While I am at it, Beta is really pronounced “vita” and delta is really pronounced “thelta”. Tau is actually “taaf” and gamma is something like “chyamma”.

    • says

      Good thought, but there are variants and regional differences in any language, especially across languages, and that does not make one any less valid than another. Ask an English person and French person to say “Paris,” or an English person and an American to say “schedule.” The words are “supposed” to be pronounced in a way that is commonly accepted and understood by the group who is speaking them.

    • Bernd Fleischmann says

      You are mixing Ancient and Modern Greek. Those are really to distinct languages.

      The pronunciation like “fee” is Koine Greek and later. In classical Attic it was pronounced like “pee”. The classical pronunciations of the letters Pi and Beta would (word initially) probably both be perceived as a /b/ by English speakers; Pi with little and Beta with strong voicing, i.e. with Pi, the voice sets in about the same time as the plosive release and with Beta voicing started very noticeably before the plosive release (Bbbbbbeta). Classical Greek distinguished three and not just two series of plosives, not only /p/-/b/, /t/-/d/, /g/-/k/ as English does but three /b/-/p/-/ph/, etc. Modern European languages don’t have this any more. In Greek there was a gradual shift from /b/ to /v/ (with the sound of the Spanish “b” as an intermediary step) and of from /ph/ to /f/ (also with an intermediary step). This shift was complete in the Byzantine era (early middle ages).

      As to the vowel of “Phi”, that has never been anything else that the modern vowel of English “fee”. The pronunciation like “pie” is a development purely within English: 500 years ago, the word “pie” was pronounced like modern “pee” but then in long process the English “long i” shifted to the diphthong it is today and the “long e” became pronounced like the “long i” used to be 500 years ago but this change was never reflected in spelling. Hence the confusion.

  3. Bretton says

    I’m very surprised what is considered typical in mathematical circles for this pronunciation. Between two US colleges, all of my math and physics professors pronounced it FEE. I’ve never met a frat boy who didn’t pronunce it FI.

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