Summary

To calculate the area of a circle, you can use the PI function together with the exponent operator (^). In the example shown, the formula in C5, copied down, is:

=PI()*B5^2

which calculates the area of a circle with the radius given in column B.

Generic formula

=PI()*A1^2

Explanation 

In geometry, the area enclosed by a circle with radius (r) is defined by the following formula: πr2

The Greek letter π ("pi") represents the ratio of the circumference of a circle to its diameter. In Excel, π is represented in a formula with the PI function, which returns the number 3.14159265358979, accurate to 15 digits:

=PI() // returns 3.14159265358979

To square a number in Excel, you can use the exponentiation operator (^):

=A1^2

Or, you can use the POWER function:

=POWER(A1,2)

Rewriting the formula =πr2 as an Excel formula to for the example, we get:

=PI()*B5^2

Or:

=PI()*POWER(B5,2)

The result is the same for both formulas. Following Excel's order of operations, exponentiation will occur before multiplication.

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Dave Bruns

Hi - I'm Dave Bruns, and I run Exceljet with my wife, Lisa. Our goal is to help you work faster in Excel. We create short videos, and clear examples of formulas, functions, pivot tables, conditional formatting, and charts.

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