Inverse Tangent Calculator – Calculate arctan(x)

Find the angle in degrees or radians using the inverse tangent with the arctan calculator below.

How to Find Arctan

Arctan is a trigonometric function to calculate the inverse tangent. Arctan can also be expressed as tan-1(x).

Arctan is used to undo or reverse the tangent function. If you know the tangent of an angle, you can use arctan to calculate the angle.

To calculate arctan, use a scientific calculator and the atan function, or just use the calculator above. Most scientific calculators require the angle value in radians to solve for tan.

Inverse Tangent Formula

The inverse tangent formula is:

y = tan(x) | x = arctan(y)

Thus, if y is equal to the tangent of x, then x is equal to the arctan of y.

Inverse Tangent Graph

If you graph the arctan function for every possible value of tangent, it forms a curve from (-∞, –π / 2) to (∞, π / 2).

illustration showing the the range of possible values for arctan on a graph

Inverse Tangent Table

The table below shows common tangent values and the arctan, or angle for each of them.

Table showing common tangent values and inverse tangent values for each in degrees and radians.
Tangent Angle (degrees) Angle (radians)
-∞ -90° π / 2
-√3 -60° π / 3
-1 -45° π / 4
√3 / 3 -30° π / 6
0 0
√3 / 3 30° π / 6
1 45° π / 4
√3 60° π / 3
90° π / 2

You might also be interested in our inverse sine and inverse cosine calculators.