Greek Small Letter Pi π

The Greek Small Letter Pi character (π) is a standard HTML entity defined in the HTML specification. In HTML source code, it can be written using the named entity reference π, the decimal numeric character reference π, or the hexadecimal numeric reference π. The character is assigned Unicode code point U+03C0 in the Universal Character Set.

Pi is the sixteenth letter of the Greek alphabet and one of the most famous mathematical constants. It represents the ratio of a circle's circumference to its diameter (approximately 3.14159). Pi appears throughout mathematics, physics, and engineering in formulas involving circles, spheres, waves, and probability distributions.

Greek letter entities are indispensable for scientific papers, engineering documentation, statistical analyses, and mathematical content published on the web. From physics equations using alpha and omega to statistical formulas featuring sigma and mu, these entities allow content authors to include Greek characters reliably without requiring specialized fonts or complex Unicode input methods on the keyboard.

When deciding how to encode the Greek Small Letter Pi character in your HTML documents, the named entity π is generally the most readable choice for developers reviewing or maintaining source code. The decimal form π and hexadecimal form π are equally valid alternatives that work in contexts where named entities may not be supported, or when generating HTML output programmatically from server-side code. All three representations produce identical visual output in every modern web browser.

Use the pi entity in mathematical formulas (area = πr², circumference = 2πr), trigonometry, physics (wave equations), and statistics (normal distribution). Pi is perhaps the most universally recognized mathematical symbol and is essential for any web content involving circular or periodic mathematics.