Please Note: This article is written for users of the following Microsoft Excel versions: 2007, 2010, and 2013. If you are using an earlier version (Excel 2003 or earlier), this tip may not work for you. For a version of this tip written specifically for earlier versions of Excel, click here: Strange ATAN Results.

Strange ATAN Results

by Allen Wyatt
(last updated October 23, 2021)

Jerry notes that when he uses the ATAN function in Excel to calculate an arctangent, he gets a result that's quite a bit different from the result provided when he uses a scientific calculator to derive the arctangent. This makes him wonder if there is something strange in how the ATAN function works.

There are two possibilities here. The most likely possibility is that your calculator defaults to using degrees in trigonometric functions such as calculating an arctangent. Excel uses radians exclusively. For example, let's say you wanted to calculate the arctangent for 0.5. If you plug this into your calculator, and your calculator is working in degrees, you'll get a rounded result of 26.565. However, using the ATAN function in Excel produces a rounded result of 0.464.

The result that Excel provides is in radians, and when you convert that result to degrees, you end up with 26.565—the same as your calculator's result. Here's how you can easily do the conversion:

=DEGREES(ATAN(0.5))

If the angle for which you want to find the arctangent is expressed in degrees instead of radians, then you'll need to do the conversion on the input:

=ATAN(RADIANS(30))

Again, remember that the result of the ATAN function is always in radians, so you may also want to do a conversion on the output, as well.

The solution is to make sure that your calculator is working in radians mode, which should give you the same results as Excel. Either that or you need to convert Excel's results (and, possibly, input) to degrees, as shown above.

The other possibility is much less likely, but it is worth mentioning: There are some values for which the ATAN function will break down, but for which your calculator may already compensate. The best explanation of the scenarios under which this could happen is provided in this Wikipedia article:

http://en.wikipedia.org/wiki/Atan2

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (11437) applies to Microsoft Excel 2007, 2010, and 2013. You can find a version of this tip for the older menu interface of Excel here: Strange ATAN Results.

Author Bio

Allen Wyatt

With more than 50 non-fiction books and numerous magazine articles to his credit, Allen Wyatt is an internationally recognized author. He is president of Sharon Parq Associates, a computer and publishing services company. ...

MORE FROM ALLEN

Changing the Type of Page Numbers Used in Headers or Footers

Like to have your page numbers displayed using different types of numbers? Here's how you can choose from the several ...

Discover More

Printing Row Numbers

On-screen Excel displays row numbers that help you easily see what is in each row. If you want to print these row ...

Discover More

Understanding Storage Spaces

Need to add some additional drive space to your system? Why not consider adding what Microsoft calls a "storage space?" ...

Discover More

Save Time and Supercharge Excel! Automate virtually any routine task and save yourself hours, days, maybe even weeks. Then, learn how to make Excel do things you thought were simply impossible! Mastering advanced Excel macros has never been easier. Check out Excel 2010 VBA and Macros today!

More ExcelTips (ribbon)

Indirect References to a DSUM Parameter

Indirect references can be very helpful in formulas, but getting your head around how they work can sometimes be ...

Discover More

Returning Values to the Left of a VLOOKUP

VLOOKUP is a great function to use in accessing data based on a lookup value. Problem is, you can't easily return ...

Discover More

Using the REPT Function

Excel includes a handy function that allows you to repeat characters or strings of characters. How you use the REPT ...

Discover More
Subscribe

FREE SERVICE: Get tips like this every week in ExcelTips, a free productivity newsletter. Enter your address and click "Subscribe."

View most recent newsletter.

Comments

If you would like to add an image to your comment (not an avatar, but an image to help in making the point of your comment), include the characters [{fig}] (all 7 characters, in the sequence shown) in your comment text. You’ll be prompted to upload your image when you submit the comment. Maximum image size is 6Mpixels. Images larger than 600px wide or 1000px tall will be reduced. Up to three images may be included in a comment. All images are subject to review. Commenting privileges may be curtailed if inappropriate images are posted.

What is one minus 1?

There are currently no comments for this tip. (Be the first to leave your comment—just use the simple form above!)


This Site

Got a version of Excel that uses the ribbon interface (Excel 2007 or later)? This site is for you! If you use an earlier version of Excel, visit our ExcelTips site focusing on the menu interface.

Newest Tips
Subscribe

FREE SERVICE: Get tips like this every week in ExcelTips, a free productivity newsletter. Enter your address and click "Subscribe."

(Your e-mail address is not shared with anyone, ever.)

View the most recent newsletter.