ATAN2 in Google Sheets: Use X-First Coordinates for Direction

• Introduced: original service launch date is not established by the official history reviewed; Sheets has no corresponding numbered desktop release in this guide.
• Availability: documented in the rolling Google Sheets service; examples use an ordinary web spreadsheet and numeric cells.
• Checked: October 14, 2026; official ATAN2 reference. Documentation and independent calculations, without native Sheets execution or broader client certification.

=ATAN2(x, y)

Google defines x and y as the endpoint coordinates of a line from the origin, with the returned angle measured from the x-axis in radians. Use both coordinate arguments. The same page’s isolated ATAN2(A2) sample omits one argument; the worked formulas here follow its explicit two-argument syntax instead.

Some programming libraries accept y before x. Copying a call between systems without checking the signature can produce a plausible angle for the wrong coordinate order. The examples use English names and comma separators.

=ATAN2(8,6)*180/PI()
=ATAN2(6,8)*180/PI()

Expected angles are approximately 36.869897646 and 53.130102354 degrees. Both are valid, but they describe different points. Testing only equal coordinates such as (1,1) would not expose a swapped-argument mistake.

The official help-linked published example includes positive x with both positive and negative y, corroborating the signed-radian interpretation for those controls. This is vendor documentation, not a newly executed spreadsheet test.

Enter x values 8, 8, 16 in A2:A4 and y values 6, −6, 12 in B2:B4. In C2 enter and fill down:

=ATAN2(A2,B2)*180/PI()

Expected angles are approximately 36.869897646, −36.869897646, 36.869897646 degrees. The third point is twice as far from the origin as the first but has the same direction. An angle alone cannot recover a vector’s length.

Keep both source coordinates. Forming y/x first would lose separate sign information and would be invalid when x is zero.

For point (8,6), calculate the length with =SQRT(8^2+6^2), giving 10. Put the radian angle =ATAN2(8,6) in E2. Then:

=10*COS(E2)
=10*SIN(E2)

Expected components are approximately 8 and 6. The COS and SIN calls use the radian result directly, not its degree-converted display.

Repeat the check with (8,−6): the same length 10 and negative angle reconstruct approximately 8 and −6. This tests both magnitude and signed orientation without claiming a complete native branch-boundary matrix.

For the ordinary nonzero examples above:

=MOD(ATAN2(A2,B2)*180/PI(),360)

Expected displayed directions are approximately 36.869897646, 323.130102354, 36.869897646. The negative angle receives a different full-turn representation, not a different physical direction.

The coordinate convention is mathematical angle from the x-axis. It is not automatically a compass bearing measured clockwise from north. State the desired axis and orientation before applying a conversion.

At (0,0), there is no mathematical direction. Google’s short reference and linked sample do not establish an exact native origin error code or every branch endpoint. This guide therefore does not copy Excel’s origin error or another product’s numeric-origin convention.

Use an explicit scalar policy such as =IF(AND(A2=0,B2=0),"No direction",ATAN2(A2,B2)*180/PI()) when a label is appropriate. The intended origin output is No direction. Test the actual workbook if array evaluation, signed zeros or imported types matter; this control is not a universal evaluation-order guarantee.

Retain the raw coordinates and test boundary cases in the target service before relying on exact native behavior beyond the finite examples shown here.

• Google ATAN2 help.
• Editorial testing standards.

Worked inputs are fictional and outputs independently calculated. Approximate values are rounded mathematical expectations, not captured native results. Imported types, extreme magnitudes and a complete error/coercion matrix remain outside the tests.