Excel PI Function

The Excel PI function returns the mathematical constant called 𝜋 (pi), which is 3.14159265358979.

The PI function is a built-in function in Excel that is categorized as a Math/Trig Function. It can be used as a worksheet function in Excel. As a worksheet function, the PI function can be used as part of a formula in a worksheet cell.

Syntax

PI()

Parameters

No parameter is required.

Return Value

Returns the value of 𝜋 (pi).

Example: Using as Worksheet Function

The example below shows how to use the PI function as worksheet function.

Based on the Excel spreadsheet above, the output of the following worksheet formula will be:

=PI()
Result: 3.14159265358979

=E5 * PI()/180
Result: 0

=E6 * PI()/180
Result: 0.785

=E7 * PI()/180
Result: 1.571

=E8 * PI()/180
Result: 2.356

=E9 * PI()/180
Result: 3.142

=E10 * PI()/180
Result: 3.927

=E11 * PI()/180
Result: 4.712

=E12 * PI()/180
Result: 5.498

=E13 * PI()/180
Result: 6.283

Example: Converting Degrees to Radians

A half-rotation (180°) in radians is equal to 3.142.. or 𝜋. An angle in degrees can be converted into radians by multiply it by PI()/180 or by using the RADIANS function. For example, to convert 60 degrees into radians, the following formula can be used:

=60 * PI()/180
Result: 1.0471975511966

=RADIANS(60)
Result: 1.0471975511966

Example: Area of a circle

The constant 𝜋 appears in many mathematical formulas. For example, the area of a circle with radius r is defined as 𝜋r². The area of a circle with radius 5 can be calculated as:

=PI()*5*5
Result: 78.5398163397448