The Excel PI function returns the constant π to 15 digits (3.14159265358979) — takes no arguments and is the building block for circle math, radian conversions, and trigonometry.
Syntax
| Argument | Description | |
|---|---|---|
(none) | Optional | PI takes no arguments, but the empty parentheses are required: write PI(), not PI. |
How to use it
PI returns π accurate to 15 significant digits. The parentheses are mandatory even though there is no argument:
PI underpins the angle conversions too: RADIANS(d) is d*PI()/180 and DEGREES(r) is r*180/PI().
Forgot the parentheses? Typing =PI alone returns a #NAME? error because Excel reads it as an undefined name. Always include the empty ().
Try it: interactive demo
Pick a PI example to see the formula and its result.
Practice workbook
Frequently asked questions
How accurate is Excel's PI function?
Why does PI need empty parentheses?
() tells Excel to call it. Writing =PI alone returns a #NAME? error.How do I find the area of a circle with PI?
=PI()*r^2. For a radius of 5, =PI()*5^2 returns about 78.54.Can I get more digits of pi than PI provides?
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