The Excel SIN function returns the sine of an angle. Excel measures angles in radians, so degrees must be converted with RADIANS or π first.
Syntax
| Argument | Description | |
|---|---|---|
number | Required | The angle in radians whose sine you want. Convert degrees with RADIANS(deg) or deg*PI()/180. |
How to use it
The most common mistake is feeding SIN a number of degrees. Excel expects radians, so wrap the angle in RADIANS():
SIN pairs with COS and TAN for the other ratios, and with ASIN for the inverse (which returns an angle in radians — wrap it in DEGREES to read it back as degrees).
Why isn't SIN(PI()) exactly 0? PI() is a finite decimal approximation of π, so =SIN(PI()) returns roughly 1.2E-16 — effectively zero, just limited by floating-point precision.
Try it: interactive demo
Enter an angle in degrees — the demo converts it with RADIANS and returns the sine.
Practice workbook
Frequently asked questions
Why does SIN(30) not give 0.5?
=SIN(30) is the sine of 30 radians (about -0.988). For 30 degrees use =SIN(RADIANS(30)).How do I convert degrees to radians?
RADIANS(deg), or multiply by π/180: deg*PI()/180. Both give the same result.What is the inverse of SIN?
ASIN returns the angle (in radians) whose sine is a given value. Wrap it in DEGREES to read the angle in degrees.Why isn't SIN(PI()) exactly zero?
PI() is a finite approximation of π, so SIN(PI()) returns about 1.2E-16 — effectively 0, limited by floating-point precision.Master functions like this in one day
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