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Excel RADIANS Function

Excel RADIANS function
Summary 

The Excel RADIANS function converts degrees to radians. For example, =RADIANS(180) returns 3.1415 or the value of π (pi).

Purpose 
Converts degrees into radians
Return value 
Radians
Syntax 
=RADIANS (angle)
Arguments 
  • angle - Angle in degrees to convert to radians.
Version 
Excel 2003
Usage notes 

The RADIANS function takes an angle in degrees and converts it to radians. Radians measure angles using the radius of a circle. For example, to convert a 45 degree angle to radians the formula is:

=RADIANS(45) // Returns 0.785 or π/4

Explanation

Radians are a unit of measure for circles

One radian is equal to the amount of rotation required to travel one radius along the circumference of the circle, as seen in the image above. A full-rotation or 360° in radians is equal to the value of 2π. A half-rotation or 180° in radians is equal to the value of geometric constant π (pi).

= RADIANS(360) =2*PI() // A full rotation is 6.283...
= RADIANS(180) =PI() // A half rotation is 3.141...

Notes

  • To convert radians to degrees, see the DEGREES function.
  • A full-rotation (360°) in radians is equal to 6.283 or 2π
  • A half-rotation (180°) in radians is equal to 3.142 or π (pi).
Related functions 
Excel DEGREES function
Excel DEGREES Function
The Excel DEGREES function converts angles (expressed in radians) to degrees. For example, the formula =DEGREES(PI()) returns 180.
Excel PI function
Excel PI Function

The Excel PI function returns the value of the geometric constant π (pi). The value represents a half-rotation in the radian angle system. The constant appears in many formulas relating the circle, such as the area of a circle.

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