The Phi Symbol

Φ vs. Ø:  Will the real Phi please stand up!

In the texts of ancient Greece, the letter phi looked like this:


When you see the Greek letter Phi on a fraternity or sorority house, it usually looks like this:


When you see Phi on a web site, it often looks like this:


What’s the slant on this?

Is Phi no longer the upright character it once was?  Has Phi become an empty shell of its former self? (A little set humor for you mathematicians.) Is Phi leaning to the right in its political orientation?  To keep Phi from suffering from an “identity” crisis (a little more math humor), here’s an explanation of what’s going and what you can do to be sure that Phi remains in good standing.

Just like golf, it’s all in the stroke

The simple truth is that the basic Western character set on computers does not include a character for the Greek letter phi.  The only basic ASCII character that comes close in appearance to Phi Φ is the letter O with a stroke through it, or Ø.  As a result, Ø has been masquerading as Φ since the early days of computer usage.

Type a real Φ on your keyboard with Alt-1000

Now that extended character sets are available on most PC’s and in most browsers, it’s possible once again to let Phi be Phi.  All you have to do is hold the Alt key and then enter 1000 on the number pad.

If your PC doesn’t have the necessary character sets installed to do this, you can use Windows’s Character Map program.  To open Character Map, click Start, point to All Programs, point to Accessories, point to System Tools, and then click Character Map.  Scroll down to find the phi symbol, click on select, then copy and paste it into your application.

Letting Φgønes be Φgønes

And while change is always bound to cause some dispute, in the end it’s better to let Φgønes be Φgønes.

Symbol font and Phi:  Alt-618 gives … j, which is phi, 0.618!

On a PC using Symbol font, you can generate a phi symbol in the following ways:

Appropriately enough, a lower case phi, or 0.618, and the reciprocal of Phi, 1.618, can be created with Alt-618: j

Other phi symbols can be created with:

Alt-70:  F

Alt-102:  f

Alt-106 or Alt-618:  j

Note:  Alt-618 means hold down the Alt key, enter 618 on the numeric pad and then release.  This insight was contributed by W. Nathan Saunders.

Running a character check on Phi


LetterGreek Letter PhiLatin letter O with stroke
CaseUpper caseLower caseUpper caseLower case
Windows character MapAlt-03A6
(0934 decimal
in HTML)
(0966 decimal
in HTML)
Type from keyboard withAlt-1000Alt-1005Alt-0216Alt-0248
Verdana fontΦφØø
Arial fontΦφØø
Times New RomanΦφØø

This page is dedicated to Katie (a.k.a. Princess Kate), a high school senior who wrote to question the usage of Ø and who inspired me to dig deeper into the reasons that the Φ symbol wasn’t being used much on web sites … until now.  (3/15/2003, The “Phides” of March, a date made from the Fibonacci series numbers of  0, 1, 2, 3 and 5)


  1. John Barltrop says

    Ø I used this symbol for the Greek letter Phi with the diagonal line through the O well over 50 years ago (Nearly 60 as a matter of fact). The first time that I recall using this letter was for the symbol for phenolphthalein (ØØ) which was an indicator solution………and I think that that was a couple of years before we started using computers……….as far as I can recall.

  2. says

    Hi! Just adding a few points:
    1) In mathematics, it is common practice to write variables in italics, and thus to have a slanted φ (or ϕ), although nowhere as slanted as an ø.
    2) The stroked O (Ø) is NOT an ASCII character. It is however available in both the ISO-8859-1 and Windows-1252 character sets, at positions 216 (upper case) and 248 (lower case).
    3) Phi (Φ) is not available in those character sets, and thus cannot be input on old Windows systems based on Windows-1252. It was, however, available in the old code page 437 of the original IBM-PC, at positions 232 (upper case) and 237 (lower case). The Alt trick is a compatibility feature designed to access characters by their code point in this legacy code page. Ah, BTW, 1000 = 232 (mod 256), that’s why Alt-1000 works like Alt-232.
    4) Modern operating systems are based on Unicode, and have thus many thousands of characters available, and means to input them, if not the fonts to display them. On Windows: Alt-0+decimal-code, on Ubuntu: Ctrl-Shift-U + hex-code + space.
    5) The Unicode code points for phi (dec/hex) are: Φ: 934/3A6, φ: 966/3C6, ϕ: 981/3D5.
    6) The Symbol font is a dirty pre-Unicode kludge where (semantically) Latin characters are given the APPEARANCE of Greek (or other) characters. You don’t need Alt codes with it, just type the letters ‘f’, ‘F’ or ‘j’ and you will get… an ‘f’, ‘F’ or ‘j’, but they will LOOK like ‘Φ’, ‘φ’ or ‘ϕ’ respectively. To someone who doesn’t have this font (I don’t), they still look like what they are, i.e. ‘f’, ‘F’ or ‘j’. There is no valid reason to use this kludge now that we have a Unicode-based Web.
    7) The Wikipedia page on phi (section computing) has more detailed information on the different characters and glyphs that can represent phi.

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