Excel ATAN Function

The Excel ATAN function returns arctangent (inverse tangent) of a number. It returns result expressed in radians.

The ATAN 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 ATAN function can be used as part of a formula in a worksheet cell.

Syntax

ATAN(number)

Parameters

Return Value

Returns the arctangent of a value.

Notes

• To convert the result in degrees, multiply it by 180/PI() or use the DEGREES function.
• If the argument is a non-numeric value, ATAN returns #VALUE! error.

Example: Using as Worksheet Function

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

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

=ATAN(B5)
Result: -1.373400767

=ATAN(B6)
Result: -1.249045772

=ATAN(B7)
Result: -0.785398163

=ATAN(B8)
Result: 0

=ATAN(B9)
Result: 0.785398163

=ATAN(B10)
Result: 1.249045772

=ATAN(B11)
Result: 1.373400767

Example: Convert Result to Degrees

To get the result from ATAN function in degrees, the result can be multiplied by 180/PI(). Alternatively, the angle can be converted into degrees by using DEGREES function. For example, to convert 2 radians into degrees, the following formula can be used:

=2 * 180/PI()
Result: 114.591559026165

=DEGREES(2)
Result: 114.591559026165

Example: PI() Function

A half-rotation (180°) in radians is equal to 3.142.. or 𝜋. A full-rotation (360°) in radians is equal to 6.283.. or 2𝜋. To get the value of 𝜋, Excel PI function can be used.

=PI()
Result: 3.14159265358979

=DEGREES(PI())
Result: 180