MS Excel: ACOS Function (WS)

This Excel tutorial explains how to use the Excel ACOS function with syntax and examples.


The Microsoft Excel ACOS function returns the arccosine (in radians) of a number.


The syntax for the Microsoft Excel ACOS function is:

ACOS( number )

Parameters or Arguments

number is a number between -1 and 1. It is the cosine of the angle that you wish to find.

Applies To

The ACOS function can be used in the following versions of Microsoft Excel:

  • Excel 2013, Excel 2011 for Mac, Excel 2010, Excel 2007, Excel 2003, Excel XP, Excel 2000

Type of Excel Function

The ACOS function can be used in Microsoft Excel as the following type of function:

  • Worksheet function (WS)

Example (as Worksheet Function)

Let's look at some Excel ACOS function examples and explore how to use the ACOS function as a worksheet function in Microsoft Excel:

Microsoft Excel

Based on the spreadsheet above, the following Excel ACOS examples would return:

Result: 2.498091545

Result: 1.570796327

Result: 0.722734248

Result: 1.369438406