Pronouncing Phi - The Golden Ratio: Phi, 1.618

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 Dictionary.com.

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.