Pi
The pi symbol comes in three forms: π, Π and the variant ϖ. Tap one to copy it, then see the codes, how to type pi on a keyboard, and how the number π differs from the product sign ∏ and other lookalikes.
By Maya Chen, lettering designer and type educator · Checked by Jordan Hale · · How we review content
Copy pi
One tap copies one character. Each form below has its own code point.
Key facts
- Pi is the 16th letter of the Greek alphabet, with a numeral value of 80.
- Lowercase π is U+03C0, capital Π is U+03A0 and the variant ϖ is U+03D6, while the product sign ∏ is a separate character, U+220F.
- The circle constant π is about 3.14159 and is irrational and transcendental, so its decimals never end or repeat.
- The constant was named with the first letter of the Greek words for periphery and perimeter, according to Wikipedia.
- In code, Python math.pi, JavaScript Math.PI and Excel PI() give the number without typing the symbol.
Codes for every form
Unicode names and code points for each form, with the escapes you need in HTML, CSS, JavaScript and LaTeX.
| Form | Unicode name | Code point | Decimal | HTML | CSS / JavaScript | LaTeX |
|---|---|---|---|---|---|---|
| pi, lowercase | GREEK SMALL LETTER PI | U+03C0 | 960 | π π | \03C0 / \u03C0 | \pi |
| pi, capital | GREEK CAPITAL LETTER PI | U+03A0 | 928 | Π Π | \03A0 / \u03A0 | \Pi |
| pi symbol, variant lowercase | GREEK PI SYMBOL | U+03D6 | 982 | ϖ ϖ | \03D6 / \u03D6 | \varpi |
How to type pi
The quick methods for this letter. Step-by-step instructions for each system, and what we have and have not tested, are on how to type Greek letters.
| Method | What to do |
|---|---|
| Copy and paste | Use the buttons at the top of this page. Pasted text is plain Unicode. |
| Word on Windows | Type the code, then press Alt+X: 03C0 for π; 03A0 for Π; 03D6 for ϖ. Windows steps. |
| Excel and Google Sheets | =UNICHAR(960) for π; =UNICHAR(928) for Π; =UNICHAR(982) for ϖ. Office steps. |
| Windows Alt code | Hold Alt and type on the numeric keypad: 227 gives π. From the old code page 437 table; not tested by us on a live Windows machine. |
| Mac Option key | On a US layout: Option+P gives π. Layouts differ by country, and we have not tested every macOS version. Mac steps. |
| Phone | Add a Greek keyboard: iPhone and iPad or Android. |
| Web page or LaTeX | π, \pi for π; Π, \Pi for Π; ϖ, \varpi for ϖ. LaTeX commands work in math mode. |
Characters that look like pi
These are separate characters, so each has its own code point. Copy the one that matches the job.
How to say pi
| Reading | Value |
|---|---|
| English (maths and science) | PIE, /paɪ/ |
| Modern Greek | /p/. The modern Greek name is πι, /pi/. |
| Classical Greek (reconstructed) | /p/. The classical name is often given as πεῖ, /peː/. |
English speakers say "pie" for the symbol and for the number. Wikipedia gives /piː/ or /peî/ for the Greek name; the ancient pronunciation is a reconstruction, so treat it as the scholarly consensus. Pi stands for a /p/ sound in every period of Greek. See the pronunciation page for the whole alphabet.
What pi means, field by field
"Standard" marks a definition or notation that is fixed, such as an SI unit or a named function. "Convention" marks common practice that varies by author, so check the definitions in your own text. The same letter often means different things in different fields; the full table for every letter is on Greek letters in math and science.
Geometrysymbol πStandard
The ratio of a circle's circumference to its diameter, about 3.14159. It gives circumference C = 2πr and area A = πr². It is an irrational and transcendental number, so its decimals never end or repeat.
Trigonometry and physicssymbol π radStandard
Radians measure angles by arc length, so 180° is π radians and a full turn is 2π. Angular frequency follows from the ordinary frequency as ω = 2πf.
Mathematicssymbol ΠStandard
Capital pi means "multiply these", like Σ means "add these". Π from k = 1 to n of k equals n!, the factorial.
Number theorysymbol π(x)Standard
The prime-counting function, which counts primes up to x. π(10) = 4 because 2, 3, 5 and 7 are prime. Here π is a function name, not the circle constant.
Chemistrysymbol π bond, ΠConvention
A pi bond is formed by sideways overlap of p orbitals and sits above and below the line between nuclei. Capital Π is also the usual symbol for osmotic pressure.
Particle physicssymbol πStandard
The pion, a light meson, takes its name and symbol from the letter. It comes as π⁺, π⁻ and π⁰.
Astronomysymbol ϖConvention
The variant pi stands for the longitude of periapsis, a quantity that describes the orientation of an orbit. This is a case where ϖ and π are not interchangeable.
Economics and lawsymbol π, ΠConvention
Economics texts often use π for profit or inflation. In informal legal shorthand, Π has stood for the plaintiff.
Lookalikes and common mistakes
ϖ is not π
The variant ϖ (U+03D6) looks like ω with a bar and is a separate code point. It is used as its own symbol in some physics and astronomy texts, so swapping it for π changes the meaning. If you want the circle constant, use π (U+03C0).
Π is not ∏
Capital Π (U+03A0) is a letter and ∏ (U+220F) is the product operator. They look alike in some fonts. Use ∏ in a formula that means a product and Π when pi is a letter, for example in a name or as a variable.
Typing π into a cell does not give you the number
A π you paste into Excel or Sheets is text. Use =PI() in a spreadsheet, math.pi in Python or Math.PI in JavaScript to get the numeric value, about 3.14159265358979 to fifteen digits.
Cyrillic П and п look like Greek
Cyrillic П and п are different letters that resemble Π and π in some fonts. If you copy from a source that mixes alphabets, searches and sorting will treat them as foreign text. Copy from the buttons above.
Small π can be mistaken for n
In handwriting and small type, π and n are easy to confuse, as are ν and v. Inspect the glyph if a formula looks odd, and check the code point if the text will be machine-read.
Where does the pi symbol come from?
Pi is the 16th letter of the Greek alphabet with a numeral value of 80. It comes from the Phoenician letter pe, and the Latin P and Cyrillic П descend from it, according to Wikipedia. The number π carries the letter because it is the first letter of the Greek words for periphery and perimeter, the lengths that the constant relates to the diameter.
Wikipedia also notes that π is exactly half of the circle constant τ (tau, 2π), which some authors prefer. Both appear in formulas, and 2π shows up so often that τ was proposed as a shorter way to write it. Most textbooks still use π, so it is the one to know.
Which pi do you need?
Use π for the number and for the letter in running Greek text. Use Π when you mean a product in a formula or when a name needs a capital. Use ϖ only when a source tells you to, since it is a separate symbol with a different meaning in the fields that use it. And if you are writing a program, you do not need the symbol at all: every language has the constant under another name.
In a table of characters:
| You want | Use | Code point |
|---|---|---|
| The circle constant in text | π | U+03C0 |
| A product in a formula | ∏ | U+220F |
| The capital letter | Π | U+03A0 |
| Variant pi from a physics text | ϖ | U+03D6 |
How do you write π in code and markup?
In HTML, π, Π and ϖ are named entities, and π is the numeric form. In CSS, the escape is \03C0. In JavaScript or Python strings, use \u03c0. In LaTeX math, \pi, \Pi and \varpi give the three forms. For the number itself, a program should call the constant: math.pi in Python, Math.PI in JavaScript, PI() in Excel and Sheets.
Sources
These sources back the facts on this pi symbol page. Field meanings are conventions, so use the definition your own text gives.
- Wikipedia, Pi (letter) (origin, name, uses of π, Π and ϖ)
- Wikipedia, Pi (the constant, its irrationality and transcendence)
- Unicode Greek and Coptic code chart (PDF)
- Microsoft Support, UNICHAR function
- Mac, Alt code and field conventions are standard but not all were tested by us; see how to type Greek letters for what is verified.
Frequently asked questions
Basics
What is the difference between π, Π and ϖ?
What does the pi symbol mean?
Where it works
Where is capital Π used?
What does π(x) mean in number theory?
How it works
How do I type the pi symbol on a keyboard?
How do I write pi in code without typing the symbol?
Tips & limits
Is the pi symbol the same in all fonts?
Why is pi sometimes written as 3.14?
What is the difference between π and τ?
Is the product sign ∏ the same as capital Π?
Related Greek pages and symbols
- Greek Letters in Math and ScienceGreek letters in math and science are conventional symbols: π is the circle constant, Δ a change, σ a standard deviation, λ a wavelength and Ω the SI ohm. Only a few meanings are fixed by standards, so they vary by field and author. Look up a letter below; each one lists its meanings grouped by field.
- How to Type Greek LettersHow to type Greek letters on any device: add a Greek keyboard on Windows, Mac, iPhone or Android, or use Alt+X in Word and UNICHAR in Excel for a single character. Copying from the alphabet page works everywhere. Each method notes what we verified and which traps to avoid.
- Greek Alphabet UnicodeThe Greek alphabet Unicode block, Greek and Coptic (U+0370 to U+03FF), holds all 24 letters: capitals at U+0391 to U+03A9 and lowercase at U+03B1 to U+03C9. This page lists each code point, HTML entity and LaTeX command, plus the micro sign, ohm sign and homoglyph traps.
- Math SymbolsTap a symbol to copy it. Every symbol shows its Unicode name and code point, and the page explains which lookalikes to avoid.
- Greek Alphabet PronunciationGreek alphabet pronunciation depends on the tradition: modern Greek is what Greeks speak today, classical Greek is a scholarly reconstruction of fifth-century BC Athens, and English readings are the letter names used in maths, science and Greek life. This page gives every letter in IPA for all three, with no audio.
- Greek AlphabetThe Greek alphabet has 24 letters, from alpha to omega, each with an uppercase and a lowercase form. Tap any letter to copy it, check its name, sound and numeric value in the table, or print a clean one-page chart. This page treats the letters as characters and symbols, not as a language course.