Excel Function Translator Logo
    The Excel Translator

    COS

    Math & Trig

    Returns the cosine of an angle specified in radians.

    Translations
    EnglishCOS
    FrenchCOS
    SpanishCOS
    GermanCOS
    ItalianCOS
    PortugueseCOS
    DutchCOS
    PolishCOS
    RussianCOS
    TurkishCOS
    CzechCOS
    HungarianCOS
    SwedishCOS
    DanishCOS
    FinnishCOS
    Syntax
    COS(number)

    Arguments

    • numberThe angle in radians
    Examples
    =COS(0)
    1

    Cosine of 0 radians is 1

    =COS(PI())
    -1

    Cosine of PI radians (180 degrees) is -1

    =COS(RADIANS(60))
    0.5

    Cosine of 60 degrees is 0.5

    Tips & Best Practices
    • •Argument must be in radians, use RADIANS() to convert degrees
    • •Result is always between -1 and 1
    • •COS(0) = 1, COS(PI()) = -1
    Common Mistakes
    • •Passing an angle in degrees directly to COS without converting it first - COS expects radians, so COS(90) doesn't give the cosine of 90 degrees, and RADIANS(90) needs to be used instead
    • •Expecting COS(0) or similar familiar values to return a perfectly round decimal - floating-point precision can produce results like 1 or extremely close to it but not always displayed as a perfectly clean number
    • •Confusing COS with ACOS - COS takes an angle and returns a ratio, while ACOS takes a ratio and returns an angle, and using the wrong one inverts the intended calculation
    Related Functions
    SINCalculates the sine of an angle, the complementary trigonometric function often used alongside COS.
    ACOSPerforms the inverse operation - takes a cosine value and returns the corresponding angle in radians.
    RADIANSConverts a degree value into radians, the unit COS expects for its angle argument.
    Frequently Asked Questions

    Why doesn't COS(90) give me 0 like the cosine of 90 degrees should?

    COS expects its input in radians, not degrees. Use COS(RADIANS(90)) to correctly calculate the cosine of a 90-degree angle.

    What's the difference between COS and ACOS?

    COS takes an angle (in radians) and returns a ratio between -1 and 1. ACOS does the reverse - it takes that ratio and returns the corresponding angle.

    Why does COS(0) sometimes not look like a clean 1?

    Floating-point arithmetic can introduce tiny precision artifacts, though COS(0) should return exactly 1 in practice - very close results for other angles are more commonly affected by this.

    Need to translate a formula using COS?

    Use our translator to convert your complete formula