PI function
PI returns the constant π, accurate to 15 digits (3.14159265358979). It takes no arguments, but it still needs its empty brackets. Use it for anything with circles: areas, circumferences, cylinder volumes and converting degrees to radians.
- Available in
- Every current version
- Category
- Math functions
- Returns
- π, to 15 significant digits.
- Google Sheets
- Works the same in Google Sheets.
Syntax
=PI()
| Argument | Required? | What it is |
|---|
Examples
Each result below is calculated from the sample sheet by our formula engine, the same one that grades the practice.
| Cell | Formula | Result | What it shows |
|---|---|---|---|
| D2 | =PI() | 3.141592654 | π itself; the cell shows as many digits as fit |
| D3 | =PI()*B3^2 | 153.94 | Area of a 14-inch pizza: about 153.94 sq in |
| D4 | =2*PI()*B3 | 43.98 | Circumference of the same pizza: about 43.98 in |
Try it live
This is the sample sheet. Change any number or text, or edit a formula, and the results update.
Show the sample data as a table
| Input | Value | ||
| Pizza diameter (in) | 14 | 3.141592654 | |
| Radius (in) | 7 | 153.94 | |
| 43.98 |
Practice PI
Graded instantly, then re-checked on changed data.
Tank volumes
Each tank is a cylinder. In
D2, use PI to calculate its volume: π × radius² × height. Fill down to D6.Common mistakes
| What you see | Why, and how to fix it |
|---|---|
| #NAME? | PI was typed without its brackets. Write =PI(), not =PI. |
| The area is four times too big | You squared the diameter. Area uses the radius: half the diameter. |
| Small differences from a textbook | Typing 3.14 loses accuracy. Use PI() instead. |
Tips
- Degrees to radians: =A2*PI()/180, the same as RADIANS(A2).
Questions
How do I use pi in Excel?
Type =PI(). For a circle's area, use =PI()*r^2.
How many digits of pi does Excel use?
15 significant digits: 3.14159265358979.
Last reviewed October 2026. Every example result on this page is calculated live by the Spreadsheet Practice formula engine.