Syntax
ATAN2(x_num, y_num)
| Parameter | Description |
|---|---|
| x_num | Parameter of the ATAN2 function. |
| y_num | Parameter of the ATAN2 function. |
Examples
First quadrant
Formula
=DEGREES(ATAN2(1, 1))
Returns 45. The point (1,1) is at 45° from the positive x-axis.
Second quadrant
Formula
=DEGREES(ATAN2(-1, 1))
Returns 135. The point (-1,1) is in the second quadrant at 135°. ATAN(1/-1) would give -45°, which is wrong.
Navigation bearing
Formula
=MOD(DEGREES(ATAN2(east_displacement, north_displacement)), 360)
Converts x,y displacement to a compass bearing (0-360°). MOD handles the wrap-around from negative angles.
Common Errors
#DIV/0!
=ATAN2(0, 0) returns #DIV/0! because the angle is undefined at the origin.
#VALUE!
Non-numeric arguments return #VALUE!.
Tips
Argument order: x first, then y
In spreadsheets, ATAN2(x, y) has x first, unlike many programming languages where it's atan2(y, x). Double-check the order.
Full 360° range
ATAN2 distinguishes all four quadrants. ATAN(y/x) can't tell (1,1) from (-1,-1) — both give 45°. ATAN2 correctly gives 45° and -135°.
Cartesian to polar
Radius = SQRT(x²+y²), Angle = ATAN2(x, y). This pair converts any (x,y) point to polar coordinates (r, θ).
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