The Excel RADIANS function converts an angle measured in degrees into radians — the conversion you almost always need before feeding an angle to SIN, COS, or TAN, which all expect radians.
Syntax
| Argument | Description | |
|---|---|---|
angle | Required | The angle in degrees you want to convert to radians. |
How to use it
RADIANS applies radians = degrees × π/180. Because Excel's trig functions all work in radians, RADIANS is the standard wrapper around any degree value:
Without it, =SIN(30) would be read as 30 radians and give the wrong answer. To convert back, use DEGREES; the two are exact inverses.
Same as ×PI()/180: =RADIANS(45) and =45*PI()/180 give identical results. RADIANS is just the clearer, self-documenting way to write it.
Try it: interactive demo
Pick a RADIANS example to see the formula and its result.
Practice workbook
Frequently asked questions
Why do I need RADIANS before SIN or COS?
=SIN(RADIANS(30)) gives 0.5, while =SIN(30) wrongly treats 30 as radians.How does RADIANS convert the value?
=RADIANS(180) = π (about 3.14159) and =RADIANS(90) = π/2.Is RADIANS the same as multiplying by PI()/180?
=RADIANS(45) and =45*PI()/180 return the same number. RADIANS is just clearer to read.How do I convert radians back to degrees?
DEGREES function, the exact inverse: =DEGREES(RADIANS(45)) returns 45.Master functions like this in one day
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